Approximately 99.999% of those complaints are uttered by people who 1) are not doing the work, 2) are not interested or capable of doing the work, and 3) do not understand or refuse to acknowledge that the Wayland and X developers are _mostly the same folks_ and they _do not want to work on X11 anymore_.
I don't really have a stake in this argument, except I'm bone-tired of seeing people whine about Wayland when they're using software somebody else gave them for free. There are enough Wayland whiners that, by now, they could've banded together and started maintaining / improving X and (if their complaints and theories were correct) left Wayland behind.
Strangely -- even though X is open source and eminently forkable (we know this, because XFree86 -> X.org) it gathers dust and none of its proponents are doing anything towards its upkeep.
When someone shows up with "Wayland isn't as good as X, so here is my modernized fork of X anyone can use" -- I'll be quite interested.