Defending Android’s Hardware Buttons(vbsteven.com)
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Defending Android’s Hardware Buttons
http://vbsteven.com/archives/521
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My not so technically inclined mother just purchased an iPhone to "keep up with the times." Her biggest difficulty with it so far is figuring out how to move around within any application, specifically going back. It's hard for her to realize that sometimes she has to hit the button called "back" sometimes it's called "cancel" and sometimes it's called something else. She would love a back button, even if it were inconsistent.
This is my intuition too. The iPhone model is a single app page swimming in a top-level sea with others. For some things, that's fine. But for many apps (browsers are obvious, but also games that have splash menus, anything with a folder-like hierarchy, etc...) there is a clear and obvious "back" metaphor. And iOS just doesn't do back.
That's not an excuse for Android apps that use it inconsistently obviously (though the framework is pretty good about making sure obvious implementations do the obvious thing). But on the whole I think it's a very good feature.
Likewise, "menu" is something that almost everything has and probably deserves a hardware button (or at least a button with a persistent location and presentation -- the Galaxy Nexus apparently has no "hardware" buttons outside the touchscreen).
The "search" button that so many Android phone have, on the other hand, is completely beyond me. Ridiculous.
That's not an excuse for Android apps that use it inconsistently obviously (though the framework is pretty good about making sure obvious implementations do the obvious thing). But on the whole I think it's a very good feature.
Likewise, "menu" is something that almost everything has and probably deserves a hardware button (or at least a button with a persistent location and presentation -- the Galaxy Nexus apparently has no "hardware" buttons outside the touchscreen).
The "search" button that so many Android phone have, on the other hand, is completely beyond me. Ridiculous.
Search button at first seemed superfluous to me also, however I have really found a few great uses. I use it all the time now:
Instead of launching the browser and then going to an web address, I can punch it in after hitting the search button. Opens browser with that address.
I never have to launch the browser and then search for something.
It's also great if you need to find someone in your contact list and dont feel like scrolling
The search button is also contextual, so that if you're within an app you can search for whatever(maps, sms etc)
Also long pressing on the search button brings up the voice commands.
Instead of launching the browser and then going to an web address, I can punch it in after hitting the search button. Opens browser with that address.
I never have to launch the browser and then search for something.
It's also great if you need to find someone in your contact list and dont feel like scrolling
The search button is also contextual, so that if you're within an app you can search for whatever(maps, sms etc)
Also long pressing on the search button brings up the voice commands.
Sure, but I don't think that's the right criteria. Any task can be made faster by associating a fixed button with it. But every fixed button has a cost. If you do a ton of "searching" then sure, this is good. My personal usage would be improved with a "go directly to email" button. Most people don't search that much. Or if they do, they do it from a desktop widget (even faster IMHO). I don't think it's an appropriate usage for the very precious physical space on the front panel.
Interesting point about the desktop widget. Initially, i believe in 1.0 and 1.5, you could click in the widget and type.
After that the widget was updated to launch the search app just like the search button. It basically became a 4 column wide search link.
After that the widget was updated to launch the search app just like the search button. It basically became a 4 column wide search link.
I always get frustrated by apps that have an embedded browser. (Facebook, Twitter, etc.) The upper left will be a back button that returns to the app, but the browsers back button is in the lower left. I know that's how Safari is on the iPhone, but man do I always hit that app's upper left back, when I really want embedded Safari's lower left back.
There are 2 things being discussed here:
1) people being confused by the back button because they don't realize it will always pop the current view of the navigationstack, which is systemwide.
2) the fact that the back, menu, search and home buttons are dedicated hardware buttons.
Explaining how 1) works does not mean that 2 is not broken. Personally I find 2 to be the interesting discussion.
Seeing how these hardware buttons are being changed to be a dedicated part of the Galaxy Nexus' touchscreen, and how not all vendors actually put all 3 buttons on there, it's not too hard to argue that something about the hardware buttons is at least flawed, if not broken.
1) people being confused by the back button because they don't realize it will always pop the current view of the navigationstack, which is systemwide.
2) the fact that the back, menu, search and home buttons are dedicated hardware buttons.
Explaining how 1) works does not mean that 2 is not broken. Personally I find 2 to be the interesting discussion.
Seeing how these hardware buttons are being changed to be a dedicated part of the Galaxy Nexus' touchscreen, and how not all vendors actually put all 3 buttons on there, it's not too hard to argue that something about the hardware buttons is at least flawed, if not broken.
Even though #2 isn't the topic of the original article, I also find it interesting. And looking over the comments it seems that most people prefer touch to hardware buttons.
I use my android mostly for calling, texting, music and instapaper (actually instafetch). I hate how I can't easily feel my phone and push a button for things like mute, or pause, or end call, or next song. Sometimes I actually have to unlock the phone with the top button, then swipe to really unlock, navigate to the right app/activity if it's not forefront, then look at the phone to see where the appropriate touch button is located.
Am I one of the few that wants more hardware buttons? And not the capacitive (fixed touch buttons) but the real buttons that maggit mentions elsewhere in these comments; buttons you can feel with your fingers.
I use my android mostly for calling, texting, music and instapaper (actually instafetch). I hate how I can't easily feel my phone and push a button for things like mute, or pause, or end call, or next song. Sometimes I actually have to unlock the phone with the top button, then swipe to really unlock, navigate to the right app/activity if it's not forefront, then look at the phone to see where the appropriate touch button is located.
Am I one of the few that wants more hardware buttons? And not the capacitive (fixed touch buttons) but the real buttons that maggit mentions elsewhere in these comments; buttons you can feel with your fingers.
I'm an Android user and I'll continue to be one in the forseeable future, but I have to agree that the back button "feels" inconsistent. There might be a logic behind how it works (OS-wide back button), but that doesn't mean it will make sense for the user. An app-level back-button makes a lot more sense to me. It should work just like it works in the browser.
That being said, I hope Google will try to get rid of all the physical buttons and "bottom bar buttons" in Android and replace them with gestures (learn from N9 Meego), so we can fully utilize 100% of the screen (and of course no more wasted front space with physical buttons, too). I think there are some phones coming out like the LG U1, which will have both a physical home button and virtual buttons with ICS. How does that make any sense? It wastes double the space.
Another feature request would be getting rid of the icons, too. I don't think icons belong in the touch world. You need bigger graphical elements, that are also richer than just an icon. I see them moving in this direction with some apps, but they need to move faster, preferably by Android 5.0.
That being said, I hope Google will try to get rid of all the physical buttons and "bottom bar buttons" in Android and replace them with gestures (learn from N9 Meego), so we can fully utilize 100% of the screen (and of course no more wasted front space with physical buttons, too). I think there are some phones coming out like the LG U1, which will have both a physical home button and virtual buttons with ICS. How does that make any sense? It wastes double the space.
Another feature request would be getting rid of the icons, too. I don't think icons belong in the touch world. You need bigger graphical elements, that are also richer than just an icon. I see them moving in this direction with some apps, but they need to move faster, preferably by Android 5.0.
To me it rarely feels inconsistent. I like that the back button remembers the context for whatever my current action is. It means I don't have to keep it in working memory. I just press back when I'm done.
I also disagree with Gruber's complaint:
Here’s one thing I don’t like about the Android Back button that I’ve never seen a counterargument for: it presumes that you, the user, remember the activity stack. If you turn your phone on and you’re looking at a web page in the browser, if you don’t remember what you were doing immediately before opening the web page you’re looking at, you have no idea where you’re going to go if you hit the Back button. Could be another app, could be another web page, could be the home screen. And if hitting the Back button takes you somewhere you didn’t want to go, there’s no Forward button to reverse it. It’s like leaving a breadcrumb trail in the dark — you have to remember where the breadcrumbs are because you can’t see them.
http://daringfireball.net/linked/2011/11/02/defending-androi...
Actually, I think what's nice about it is that you don't have to remember the activity stack. You just hit back if you want to go to the previous activity, and if you don't want to go to the previous activity, you go to the home screen. Why would you hit back if you didn't want to go to the previous activity and also didn't remember what the previous activity was?
Here's a common analogous scenario for me. I unlock my phone to a web page. I finish reading the web page and then go, "How did I get here?" I hit back, which usually takes me to the previous web page, to google reader, or to twitter. I then go on with what I was doing, probably skimming feeds. It's a great, natural workflow that allows me to pick up exactly where I left off.
I wonder how Gruber manages to use web browsers' back buttons without getting confused. I mean, when you hit it, it can go to SOME RANDOM WEB PAGE!
As for the forward button, it's just a matter of hitting the exact same link or button that you did the first time. Forward is redundant.
And of course, if you're ever confused, you can just hit the home button and start over. This is your only option in iOS. If you get routed to twitter from another app, and then you want to go back? Hope you remember what you were doing before. In fact, you'd better make sure you remember if you want to get back. Because you're going to have to go back through the home screen to get there.
In my scenario above, ported to iOS, if I wake up my phone to a web page, I basically have no way to go back to the activity I was doing before the web page except to just remember. That, to me, is a much worse workflow. There just aren't any breadcrumbs at all.
I also don't think there's any way to get rid of the OS-wide buttons, because there are basically two axes of navigation. There's the OS wide one along which the back button acts, and there's also the in-app one that takes you between panes of an app. Swipes already move you between panes. How can they also move you back in the activity stack?
I do agree with you that icons are outdated. I hope Android steals more from Windows Phone 7. Those tile are gorgeous.
I also disagree with Gruber's complaint:
Here’s one thing I don’t like about the Android Back button that I’ve never seen a counterargument for: it presumes that you, the user, remember the activity stack. If you turn your phone on and you’re looking at a web page in the browser, if you don’t remember what you were doing immediately before opening the web page you’re looking at, you have no idea where you’re going to go if you hit the Back button. Could be another app, could be another web page, could be the home screen. And if hitting the Back button takes you somewhere you didn’t want to go, there’s no Forward button to reverse it. It’s like leaving a breadcrumb trail in the dark — you have to remember where the breadcrumbs are because you can’t see them.
http://daringfireball.net/linked/2011/11/02/defending-androi...
Actually, I think what's nice about it is that you don't have to remember the activity stack. You just hit back if you want to go to the previous activity, and if you don't want to go to the previous activity, you go to the home screen. Why would you hit back if you didn't want to go to the previous activity and also didn't remember what the previous activity was?
Here's a common analogous scenario for me. I unlock my phone to a web page. I finish reading the web page and then go, "How did I get here?" I hit back, which usually takes me to the previous web page, to google reader, or to twitter. I then go on with what I was doing, probably skimming feeds. It's a great, natural workflow that allows me to pick up exactly where I left off.
I wonder how Gruber manages to use web browsers' back buttons without getting confused. I mean, when you hit it, it can go to SOME RANDOM WEB PAGE!
As for the forward button, it's just a matter of hitting the exact same link or button that you did the first time. Forward is redundant.
And of course, if you're ever confused, you can just hit the home button and start over. This is your only option in iOS. If you get routed to twitter from another app, and then you want to go back? Hope you remember what you were doing before. In fact, you'd better make sure you remember if you want to get back. Because you're going to have to go back through the home screen to get there.
In my scenario above, ported to iOS, if I wake up my phone to a web page, I basically have no way to go back to the activity I was doing before the web page except to just remember. That, to me, is a much worse workflow. There just aren't any breadcrumbs at all.
I also don't think there's any way to get rid of the OS-wide buttons, because there are basically two axes of navigation. There's the OS wide one along which the back button acts, and there's also the in-app one that takes you between panes of an app. Swipes already move you between panes. How can they also move you back in the activity stack?
I do agree with you that icons are outdated. I hope Android steals more from Windows Phone 7. Those tile are gorgeous.
But if I hit back to get out of an app, I don't want to return to the previous one. I want to return to a default/home setting. And I'll usually want to use a different app after that, so I'll use the homescreen or the multitasking view anyway.
Then why would you hit back instead of home?
This is only about certain behaviours of the Back button. On my Samsung phone I have four buttons on the front of the phone plus volume control and on/off buttons on the sides. The four buttons are invisible in dim light and even after using the damn thing for a year I'm uncertain of which button is where. As far as I'm concerned the buttons are broken.
I have seen the Samsung Galaxy S, and the hardware buttons on the front have several problems:
1. They are capacitive, so there is no tactile feedback ever
2. They are made to be near invisible, so you can't see them in dim light
3. The icons on the buttons are not immediately crystal clear to me
My HTC Legend has none of these problems: I can find the buttons in the dark by feel, and the iconography is clear. To me, the back and menu buttons (and to a lesser degree the home button) are helpful tools that I use all the time.
I am planning on getting a Galaxy Nexus as soon as I can. The only worry I have about this phone is the lack of proper hardware buttons that I can locate and use by feel alone.
I love (some of) the hardware buttons.
So maybe it's just Samsung's implementation of the buttons that is broken, and not the concept of Android hardware buttons. I don't know :)
1. They are capacitive, so there is no tactile feedback ever
2. They are made to be near invisible, so you can't see them in dim light
3. The icons on the buttons are not immediately crystal clear to me
My HTC Legend has none of these problems: I can find the buttons in the dark by feel, and the iconography is clear. To me, the back and menu buttons (and to a lesser degree the home button) are helpful tools that I use all the time.
I am planning on getting a Galaxy Nexus as soon as I can. The only worry I have about this phone is the lack of proper hardware buttons that I can locate and use by feel alone.
I love (some of) the hardware buttons.
So maybe it's just Samsung's implementation of the buttons that is broken, and not the concept of Android hardware buttons. I don't know :)
I have a Samsung Captivate (AT&T's Galaxy S) and while I have been quite disappointed with the device at a high-level, my issues have not been with android or the hardware buttons.
> 1. They are capacitive, so there is no tactile feedback ever
You can enable haptic feedback or tones (cringe), neither of which has substantial effect on battery life.
> 2. They are made to be near invisible, so you can't see them in dim light
True.
> 3. The icons on the buttons are not immediately crystal clear to me
While this may be true, they quite consistent with all the other android phones. (Are you specifically concerned about the having an icon for menu instead of the "menu" text?)
> 1. They are capacitive, so there is no tactile feedback ever
You can enable haptic feedback or tones (cringe), neither of which has substantial effect on battery life.
> 2. They are made to be near invisible, so you can't see them in dim light
True.
> 3. The icons on the buttons are not immediately crystal clear to me
While this may be true, they quite consistent with all the other android phones. (Are you specifically concerned about the having an icon for menu instead of the "menu" text?)
> You can enable haptic feedback or tones (cringe)
Both of which are a poor substitute for feeling the button depress.
However, I was mostly concerned about feeling the button and the edges of the button before pressing it (to be able to use the buttons without looking), but I realize now that this might not be included in the commonly accepted meaning of "tactile feedback" ;)
> Are you specifically concerned about the having an icon for menu instead of the "menu" text?
No, but I am concerned about the poor choice of icon to represent the menu.
The back-button is understandable, but why does it go forward before it goes back?
And finally, my biggest problem: What does the icon-less button in the center of the Galaxy S do? I have no idea, and the only way to figure out is to test it. (If I have to guess, I'd say it's the home-button, which is otherwise lacking and is the closest in functionality to the icon-less iPhone-button)
(Image for reference: http://androidspin.com/wp-content/uploads/2010/07/Samsung-Ga... )
I was also thinking about what I suppose must be the home-icon on the Galaxy Nexus. ( http://www.google.com/nexus/img/content/introduction.png ) This icon exhibits the classical problem of over-abstracting. It is no more a home or house than it is a shift-key, up-arrow or pointed rock.
Compare with HTC Legend: http://cdn.cbsi.com.au/story_media/339301189/htc-legend_1.jp...
From the left:
1. Obviously a house (and therefore a home), even with a chimney, while still being clear.
2. Obviously a menu-button. You unfortunately have to read it, but it is at least unambiguous.
3. Obviously a back-button. (No forward motion)
4. Assuming that the user has learned the weird currently popular icon for search, obviously search. Otherwise not a good icon.
----
I hope this clarifies my original post :)
Both of which are a poor substitute for feeling the button depress.
However, I was mostly concerned about feeling the button and the edges of the button before pressing it (to be able to use the buttons without looking), but I realize now that this might not be included in the commonly accepted meaning of "tactile feedback" ;)
> Are you specifically concerned about the having an icon for menu instead of the "menu" text?
No, but I am concerned about the poor choice of icon to represent the menu.
The back-button is understandable, but why does it go forward before it goes back?
And finally, my biggest problem: What does the icon-less button in the center of the Galaxy S do? I have no idea, and the only way to figure out is to test it. (If I have to guess, I'd say it's the home-button, which is otherwise lacking and is the closest in functionality to the icon-less iPhone-button)
(Image for reference: http://androidspin.com/wp-content/uploads/2010/07/Samsung-Ga... )
I was also thinking about what I suppose must be the home-icon on the Galaxy Nexus. ( http://www.google.com/nexus/img/content/introduction.png ) This icon exhibits the classical problem of over-abstracting. It is no more a home or house than it is a shift-key, up-arrow or pointed rock.
Compare with HTC Legend: http://cdn.cbsi.com.au/story_media/339301189/htc-legend_1.jp...
From the left:
1. Obviously a house (and therefore a home), even with a chimney, while still being clear.
2. Obviously a menu-button. You unfortunately have to read it, but it is at least unambiguous.
3. Obviously a back-button. (No forward motion)
4. Assuming that the user has learned the weird currently popular icon for search, obviously search. Otherwise not a good icon.
----
I hope this clarifies my original post :)
Haptic feedback is not a poor substitute for feeling a button depress, it's just the current reality of having a phone with a large touchscreen. You have the choice between a (relatively) much larger screen (with option of haptic feedback), or some buttons you can depress that will eventually wear out mechanically (I bet the touchscreen would outlast a mechanical button).
The only real problem I can find with not having a mechanical button is that you may sometimes bump your finger onto one of the buttons, and will find yourself suddenly in the home screen. This actually happens to me a lot in the Nexus One, but I also blame that on failed multi-touch implementation that ends up sensing my finger in some spot it's not in, or when the capacitive sensor senses my palm holding the phone through the case.
The HTC Legend menu button isn't consistent with the design of the other buttons, and it's very ambiguous. To me 'menu' is the equivalent of the home button; I expect it to take me to the home menu. Another interpretation is that it would take me to the home menu of the current application I am using, but this function is very similar to the back button.
The back arrow doesn't symbolize a lack of forward motion (it just points right to left). There are many languages (Hebrew, Persian, Japanese. Sometimes Latin and Greek too) that read from right to left defeating the universalness of the icon.
The search icon is actually designed very well as it is consistent with most devices in the world.
On the other hand is the home icon isn't very well designed on the Galaxy Nexus, but it would be very impossible to confuse the button for a shift-key, an up-arrow, or a pointed rock (I don't understand how you got the connection between a hardware button and a rock, I feel like you are just nitpicking at this point, which is why I am nitpicking your post).
In defense of the Galaxy Nexus having 3 icons instead of 4 is really more effective (why have a menu & home button, and I don't think a lot of people use the search button), it's just too bad the icons weren't designed better.
The only real problem I can find with not having a mechanical button is that you may sometimes bump your finger onto one of the buttons, and will find yourself suddenly in the home screen. This actually happens to me a lot in the Nexus One, but I also blame that on failed multi-touch implementation that ends up sensing my finger in some spot it's not in, or when the capacitive sensor senses my palm holding the phone through the case.
The HTC Legend menu button isn't consistent with the design of the other buttons, and it's very ambiguous. To me 'menu' is the equivalent of the home button; I expect it to take me to the home menu. Another interpretation is that it would take me to the home menu of the current application I am using, but this function is very similar to the back button.
The back arrow doesn't symbolize a lack of forward motion (it just points right to left). There are many languages (Hebrew, Persian, Japanese. Sometimes Latin and Greek too) that read from right to left defeating the universalness of the icon.
The search icon is actually designed very well as it is consistent with most devices in the world.
On the other hand is the home icon isn't very well designed on the Galaxy Nexus, but it would be very impossible to confuse the button for a shift-key, an up-arrow, or a pointed rock (I don't understand how you got the connection between a hardware button and a rock, I feel like you are just nitpicking at this point, which is why I am nitpicking your post).
In defense of the Galaxy Nexus having 3 icons instead of 4 is really more effective (why have a menu & home button, and I don't think a lot of people use the search button), it's just too bad the icons weren't designed better.
Part of my confusion was that I am referencing the carrier-specific US devices. The button configuration in that image isn't available from the major US carriers. Fascinate, Vibrant, and Captivate all include the menu/home/back/search buttons across the bottom (http://www.samsung.com/us/mobile/cell-phones/all-products).
I would tend to agree that the Galaxy S image you provided offers a confusing button layout for an android device.
I would tend to agree that the Galaxy S image you provided offers a confusing button layout for an android device.
I have an older Samsung phone with a 4 way directional pad, but I sure am going to miss that. Most new phones don't have one (HTC Legend had an optical one) Having to navigate everything by touch isn't perfect either...
That's funny. I had the opposite problem with my Motorola Droid. The 4 buttons were too bright and distracting from the screen. I found an app for rooted devices that turns off the button backlights, which is fine, because I memorized the positions: back, menu, home, search.
"hardware buttons"? this article isn't defending android's hardware buttons. it's defending navigation buttons. whether they are hardware buttons or onscreen buttons is irrelevant in the context.
I wish my HTC HD7 running Windows Phone had hardware buttons. 90% of the time I've hit the capacitive search button, it was an accident.
The dominating theme here is how the button feels. This post is a great defense and the facts are straight but in the end facts don't matter. Feelings do.
Apple has done a magnificent job of creating loyal converts based on feelings. Their devices have traditionally been behind Android on a number of features (but always catch up later) because they focused on making people feel like they could accomplish the tasks they wanted to.
Android goes about adding features that are super coolnewawesometrendy and they give it to you right away and it's your job to jump in and learn how to use it. Apple will slowly introduce you to new concepts even if it means limiting functionality. The Android and iOS approaches are both valid but one is better for my mother while the other is better for me.
So when we talk about the back button on Android maybe we're missing the point? Maybe instead of discussing whether the button is inconsistent or not we should be talking about how to make the entire OS feel like it helps you get what you want to do done. I don't have all the answers but I do know a few of the right questions.
Assuming you give someone an Android phone or tablet who has no previous experience or expectations... How do you make the button feel like its consistent? What is the intent of someone pressing the button? How will the action of the button fit in with the rest of the user experience? How can we get users to know what to expect after a single use of the button? Is the button even necessary? Was the decision to include this button made because of preconceived notions such as how phones used to function before touch screens?
This might be a tad bit off topic but I feel like these ideas are a natural next step in the discussion.
Apple has done a magnificent job of creating loyal converts based on feelings. Their devices have traditionally been behind Android on a number of features (but always catch up later) because they focused on making people feel like they could accomplish the tasks they wanted to.
Android goes about adding features that are super coolnewawesometrendy and they give it to you right away and it's your job to jump in and learn how to use it. Apple will slowly introduce you to new concepts even if it means limiting functionality. The Android and iOS approaches are both valid but one is better for my mother while the other is better for me.
So when we talk about the back button on Android maybe we're missing the point? Maybe instead of discussing whether the button is inconsistent or not we should be talking about how to make the entire OS feel like it helps you get what you want to do done. I don't have all the answers but I do know a few of the right questions.
Assuming you give someone an Android phone or tablet who has no previous experience or expectations... How do you make the button feel like its consistent? What is the intent of someone pressing the button? How will the action of the button fit in with the rest of the user experience? How can we get users to know what to expect after a single use of the button? Is the button even necessary? Was the decision to include this button made because of preconceived notions such as how phones used to function before touch screens?
This might be a tad bit off topic but I feel like these ideas are a natural next step in the discussion.
> In the following article I will try to explain that this behavior is not broken. Instead it is exactly what the Android developers had in mind while designing the back button behavior.
Correct, but something being by design does not imply it not being "broken". We have plenty of examples of things with flawed designs.
Correct, but something being by design does not imply it not being "broken". We have plenty of examples of things with flawed designs.
Yes, but the main argument for the hardware back button being "broken" was that it was inconsistent. This article shows that the only thing it is inconsistent with is the iOS model of multitasking.
Personally, I think the model the designers built on activities makes perfect sense an is very interesting on a technical level, but as much as you explain them to me, it still doesn't do what I want, need or expect sometimes.
Activities are hidden, they are not a user visible concept, so you cannot easily build a mental model without knowing and consciously thinking about them. From the UI, it just looks that the button has been overloaded with two functions: changing applications and changing views in the same application, because applications and views are the two very obvious UI concepts.
I also think Matias Duarte and the Android designers agree that the back button has some problems as Android 4 now has two back buttons: the good old one on the bottom and another one on the top left that behaves just like iOS's. I'm not sure two buttons with similar but slightly different behaviors are the perfect solution but we'll see if people like it.
Activities are hidden, they are not a user visible concept, so you cannot easily build a mental model without knowing and consciously thinking about them. From the UI, it just looks that the button has been overloaded with two functions: changing applications and changing views in the same application, because applications and views are the two very obvious UI concepts.
I also think Matias Duarte and the Android designers agree that the back button has some problems as Android 4 now has two back buttons: the good old one on the bottom and another one on the top left that behaves just like iOS's. I'm not sure two buttons with similar but slightly different behaviors are the perfect solution but we'll see if people like it.
In my opinion, hardware buttons should be limited to only non-critical operations or operations with limited usage frequency (which may be an argument to why the button may be unnecessary in the first place).
A button such as the back-button on the android, is used to navigate in almost all applications. With the amount of "load cycles" the back-button experiences, it is bound to either fail or start operating inadequately [1]. If or when this happens, the phone becomes rather unusable as it is nearly impossible to navigate in applications that do not have any built in user interface options to perform the same action.
[1] I do not hold evidence for this to be true in general and my hypothesis is only backed by personal experience and the notion of failure rate in a load frequency perspective.
A button such as the back-button on the android, is used to navigate in almost all applications. With the amount of "load cycles" the back-button experiences, it is bound to either fail or start operating inadequately [1]. If or when this happens, the phone becomes rather unusable as it is nearly impossible to navigate in applications that do not have any built in user interface options to perform the same action.
[1] I do not hold evidence for this to be true in general and my hypothesis is only backed by personal experience and the notion of failure rate in a load frequency perspective.
Given how long keyboards last under far heavier and harsher loads than any phone button experiences, it's clearly not a given that a hardware button must start having problem during the lifetime of the product. But it does seem clear that manufacturers aren't interested in putting the same durability on phones as they are on keyboards, as I've seen these problems with iPhone sleep and home buttons.