Arguing over Xlib vs Wayland or whatever other insanity is entirely besides the point.
The problem is, is that the X11 legacy crap is hurtin X.org in thousands of ways and people just want to abandon the extreme latency of X.org by removing Xlib and having their shit run directly from widget toolkits. Try to resize a Window and then... aha!
But then people like to have X11 around and think that Wayland is screwing with their desires, while it's perfectly possible and needed to approach stuff in a different way than the X11 way.
You X server is just a 'browser' for X11 nework protocol. Ideally, Wayland can support X11 or X12 or whatever pretty much as well as your XServer can. (and it already supports X11)