Lots of animations do serve a clear purpose. Humans are not used to things popping up into existence immediately out of nowhere. Yes, you may argue that you and me are tech savvy and trained our brains to not care as much. But that leaves everyone else.
I think a bunch of animations shown in this piece are over the top. But quick animations can help immensely with usability. The best ones are so subtle that most people don't even notice. Interestingly, lots of game UIs have subtle animations, I guess because they are easy to do. OSX, iOS and even Android have animations _everywhere_, but they barely register unless you are looking for them (exception for windows getting minimized, but that does serve a function).
> I'm not convinced that we've seen any meaningful advance in OS UI design since Windows 95.
If that's the bar, then we haven't seen any meaningful advancements ever since the Xerox PARC.