Fixing X would require a protocol that is mostly X, but of course incompatible because you have to rip out some protocol bugs. But Wayland isn't X minus the bugs. Wayland started as a little bit of broken bitmap-pushing and a whole lot of hot air. And even with tons of extension and auxilliary protocol development, multiplied by tons of unnecessary reimplementations in tons of compositors, it isn't even where X11 was when Wayland started. Wayland fixed nothing yet, broke a lot, fragmented the community, brought pain and misery.