There's a very convincing talk I saw by Daniel Stone (X developer, Wayland developer), you can watch it on youtube. Basically X is more bad than good, and because of this no one can/wants to even implement it properly because to implement the bad parts is just insane. So by the time you fix all of X's flaws, pull out the font rendering, drivers, etc., it's not really X anymore.

http://www.youtube.com/watch?v=RIctzAQOe44

I understand people want their forwarding, but as long as I can get a remote window up on my screen, that's fine for me, and they seem to have this covered with RDP. It'd be great to get SSH integration like X currently has, but not essential.

Isn't it telling that the people developing X think it's the wrong solution for the current state of computing? Heck, even the network transparency (what I most often hear people raving about X) is just a slow way to send around bitmaps, because the rendering is rarely done using the X rendering primitives.