[cheriot]

It's definitely a risky move as your examples demonstrate, but aren't most of the Angular core developers working for Google? I don't think they have an interest in generating more consulting work.

Angular was arguably the state of the art for a while. I suspect the core team would rather pursue that position again than spend years focusing on legacy support.

I'm not terribly familiar with the perl, php, or python communities, but my understanding is that a lot of the changes made were to "fix" things and "clean up". Aka, there wasn't a "I need this to get my job done" reason to upgrade. On the other hand, client side development has progressed rapidly since Angular 1.0. Things like isomorphic javascript just won't work with the old APIs.