If in return for this we got Linux on at least 50% of desktops? Yes, the world would be a better place.
Oh, and Wayland is most certainly the epitome of "mechanism, not policy" principle. The whole Wayland is just about 10k of clear C code with minimum of policy.
All the policy is encapsulated in the compositor. Right now the reference Weston compositor is not very modular, but nothing stops you from writing XMonad compositor for Wayland. In fact, it'll work even better than XMonad on X.