I (the author) would agree that it's insane, but it's often the case that when products get created, there's only one UI developer at the start. More importantly, if you DO have all those skills, you'll keep getting those kinds of opportunities.
I'd say rather than chase after things for their perceived value, do what you love. A lot of that esoteric knowledge is just the byproduct of doing what you like to do for years on end. If you like what you're doing now, keep doing it, get better, learn more.
As for few products being built around one superhero, that's absolutely true. But it's often the case that when products get created, there's only one UI developer at the start. In the article, the guy I'm referring to was one of the first developers at simple.com - how cool is that?
JavaScript has been around long enough to arguably be called a mature language. It doesn't really need to be "better" (any more than any other language). It's the environment that's crappy - the Browser. But those aren't going anywhere. You're going to be waiting a long time before something supplants it.
I believe I say in the article that if you have 5 of the 7 things that you're in solid shape. You certainly don't have to have any of these things, but having them helps...
If you can't be bothered to author your code using only ONE JavaScript library, then yes, name space "pollution" is not very friendly. But if you write all your code using one framework, then the name space is yours to use, which to me is not pollution. It's only a pain when you want to use several frameworks, and the only reason I can imagine to to do that is to use plugins from more than one. That's laziness if you ask me; rather than ask your users to download two libraries, you should author your own version for your framework of choice.