Yeah, some (arguably most) of the missing features/core problems are due to the fact that OSX has been all-but-ignored by Apple for half a decade, but some of them are just due to the fact that the UNIX paradigms are becoming outdated. Google is trying to solve the latter problem with Fuschia, you're right, which is interesting. But so far that OS's UX also looks like it's primarily mobile-focused, even if it's designed to be adaptable to desktops too.
I think OSX's UX problems are mainly in the first category - Apple just doesn't care. Windows introduced snapping in Windows 7, nearly ten years ago. It is extremely useful and seems pretty easy to implement. As you say, you can always get a third-party application like the (fantastic) BetterTouchTool. But you shouldn't have to do that for something so fundamental. The very least Apple could be bothered to do is keep up.