One thing I've been thinking about a lot since writing this is that we just finally got into a good spot with iOS UI/UX. It took nearly a decade for the drastic over-correction of iOS 7 to smooth out and be refined, to find middle ground again. And so of course Apple throws a grenade in the room.
Keep coming back to the same question: Why? Doesn't make things better, doesn't provide new insight or UX. It's just shiny chrome that makes it harder to read things on the screen. The ecosystem will spend millions of dollars to coerce their apps into this design system for nearly no gain for users.