People run crapburgers like GNOME and then say "X is bloated and slow, we need to replace it NOW with Wayland". Uh, no, your DE is bloated and slow. X is warty and certainly worthy of criticism, but force-switching everybody to PulseVideo--sorry, Wayland, is not going to solve all the problems with the Lunix desktop and is going to introduce a whole new slew of transition-phase problems.
As you said, Wayland actually provides less than X. If you want to turn Linux into Windows, then the solution is a single, standardized, soup-to-nuts graphics layer incorporating everything from graphical primitives to widget toolkits and user-interface guidelines. Linux still has multiple toolkits and multiple DEs squabbling for mindshare, and seems to grow one more everytime GNOME pisses someone new off.
You mean "provide a flag in ssh to forward a rendered window?"
They were talking about having hooks so a VNC server could act as a compositor for windows that it can forward over the VNC protocol. That would be a much better solution than raw pixel buffers like X forwarding had.
Which is why there has been so much fuss. I haven't kept up, but has the Wayland project changed their tune on networkable graphics? I will grant that X could use some uncrustifying, but I think the general gist of the OP is correct: there is just so much that X offers that Wayland and Mir will have to catch up to (assuming they can, which requires not just time and effort, but forward thinking on design and architecture).
And as for performance, my N900, a four years old phone, runs X just fine. The sad experience I have had with software (including OSS), is that the newly born projects are almost always designed without paying attention to efficiency, usually through a lack of awareness because people are so used to fast hardware these days.