You don't need to use all of that just because it's there and having it there is more reliable than having to cobble together your own, at least in a corporate setting.

I actually find it surprising that this is a Google project, if you just gave me the code/docs and didn't tell me what project it is I would have guessed this came from Microsoft (feels much more WPF/Silverlight like than GWT/Closure, hell it even uses Rx which came out of MS)