> People have explained dozens of times by now what's wrong with X11 and why it's worth working on a replacement.
No! People have dozens of times explained why they CAN work on a replacement, not why it's worth working on it. Usually all those explanations boil down to "X11 has too many features" and "Wayland is not too bad". But nobody have ever explained who's going to win from it. I would be glad if you provide me a link to such explanation.
Wayland/Weston is like a HelloWorld-program. It's useless but IN THEORY you can extend it to do whatever you want... Hm... HelloWorld is the best graphical manager! It's fast and simple! You can do everything else client-side! Sounds familiar? :-)