Wayland is a critical technology for Linux desktop community.
X11 has been a reliable workhorse, but its time is up - simply too much cruft accumulated over the years that's not even used anymore. Yet all of it needs to be continually supported, adding to complexity. No one uses X11 primitives for drawing apart from bitmap functionality - even repainting dirty regions (expose events) often involves sending over a new bitmap and using X11 to draw it. This is very inefficient.
To implement a reasonably fast GUI, X11 has essentially resorted to hacks (extensions). DRI2 (+GLX) is probably the most important of those. AFAIK, it's what almost everything uses for drawing, and does not work over network at all. Yes, modern X11 is local only. If you're on a network, it's back sending those uncompressed bitmaps. Even with all these hacks, X11+DRI2 can't even maintain tearing free display. Well, at least DRI3 should fix tearing...
So if none of modern software needs nothing but a bitmap surface to draw on, why implement and maintain anything else?
Which leaves us with Wayland criticizers' favorite topic - network transparency (which X11 practically doesn't have either, but unfortunately that does little to stop some loud uninformed people):
Remote display software should use low latency video encoding for essentially same user experience as working locally. Preferably hardware accelerated. But even with software, you can encode a frame under 10ms, using for example a subset of h.264. Even if you added network latency, time for one frame network throughput and client display hardware retrace period, you'd still typically end up with a figure well under 50ms. That'd feel essentially local. It'd beat easily X11 over network, VNC, RDP, etc. in latency and thus practical usability. Heck, that'd even beat Xbox 360 or Playstation 3 game display latency when connected to a typical modern TV (70-170ms)! Many TVs do image processing that adds over 50ms of latency before image is actually displayed. (Note that this processing latency has nothing to do with "pixel response time").
Why no one I know of has written remote display software that functions this way is beyond me. Anyone except OnLive and Gaikai, that is...
So, let the old X11 horse have its well-earned rest. It's time to move on.