The issue is that X was never a mature, feature-complete, stable project.

Looool. It was too stable, which means stagnation.

bloated hodgepodge of disparate and barely working patches.

You mean bloated protocol or bloated implementation? Because kwin_wayland is pretty bloated.

The entire point of Wayland is to do exactly what you say tech should do: solve the particular problem (graphics server) well and cleanly, and limit itself to a definable set of features so it can actually reach that point of stability.

Tying graphics server to audio server is very clean.