I remember a discussion a year or two ago here on Slashdot how X was badly in need of replacing. Sounds to me like Canonical have the right idea, and the impetus to make it happen.
People have been saying X was in need of replacing shortly after it was created (and yes, that was before I was born). Does X have issues? Sure. Are they dealbreakers? Obviously not, otherwise X would have been dropped instead of being forked those many years ago.
I've not had a look at Wayland, but it sounds to me like the same-old, same-old whining by "end users" and "gamers", specifically "waaah! my 3D isn't fast enough!". As for the speed, 90% of users don't care how fast it is (which I might add, X is not that slow; *by far* faster than VNC and RDP over the network, and none to shabby with accelerated drivers on the local machine). As for the complexity, 90% of programmers are using a toolkit that eliminates the difficulties in programming for X. And X has it's benefits (such as network transparency, which *will* become more important in the future; this whole "network isn't important, we should optimize it out" thing is a fad).
The thing that bothers me about Wayland is that it seems to want to enforce policy and have it's own windowing system built in. I *like* the fact that there is no One True Desktop for Linux (or X); I can pick a different desktop any time I please, and still run graphical applications from my headless servers. And no, VNC and RDP don't come close; I don't want to have to dedicate a desktop just to run a single GUI app from my servers, and wait for the horribly slow refresh. I also like the fact that X is lightweight enough to run on my netbook and my smartphone. Which also means I can run graphical apps to or from either of those, and from my aforementioned headless server.
As for those saying that Wayland will probably have support for X11 "much as Windows and Mac do", I say to them, the way Windows and Mac "support" X is one of the reasons I don't run Windows or Mac.