IMO, this is about protection of revenue stream. Sale of the hardware is only the first transaction. Ongoing licensing and kickbacks from second-order sales is the second: bandwidth, app sales, accessories, etc.
If users modify their phone, they could possibly escape the locked-down universe this maker has created, and therefore metaphorically short-circuit revenue stream plans.
In short, it's about control. Manufacturer control of the user, but not user's control of the device. (Note I deliberately said "user" not "owner" since I believe that best reflects the viewpoint of the manufacturer.)
Now that you mention it, yes, it does resemble SCRATCH, and I would also suggest Lego Mindstorms programming environment.
I am showing my age, when I admit that my initial reaction was to note the similarity with Novel's AppWare circa 1995. ( http://support.novell.com/techcenter/articles/dnd19940502.ht... ) Appware, like Scratch, took a modular approach of assembling software building blocks and connecting the output of one to the input of the other, dealing with triggers, events, etc. As a programmer coding to native APIs (WinAP and MacOS, in C++) I found AppWare to be an adequate and fun prototyping tool, useful for quickly testing an idea or stringing together a quick & easy widget to solve a basic problem. Even moreso, considering it was a cross-platform (MacOS & Windows 3.0) system, which was novel for that time period. However, when it came time to build a full-featured application to deliver to others, in my experience Appware fell short. I suspect I'd feel the same way about this tool for Android but I'm willing to give it a shot.
I suspect that much of the HN readership feels the same, but we are quite the minority, and this tool is designed to address the needs of what my non-programmer wife charmingly refers to as "normal people" -- non-hacker people who don't really care how things work, but instead use the device as a tool in order to get on with their lives rather than a means unto itself.
If users modify their phone, they could possibly escape the locked-down universe this maker has created, and therefore metaphorically short-circuit revenue stream plans.
In short, it's about control. Manufacturer control of the user, but not user's control of the device. (Note I deliberately said "user" not "owner" since I believe that best reflects the viewpoint of the manufacturer.)