Aren't most of these also backportable to Python 2.7? Especially the libraries, where the reason seems to be, "we added a nifty little tool."

If so, then why the breaking language change? Why should I port my Python 2.7 code to Py3 for some libraries that I didn't feel like I was missing?

I'd suggest including more demos of how the backwards-incompatible changes made Python 3 better than 2.7.