And why wouldn't someone be happy working on X11? It is an open source project, it is high impact work. I would jump at it instantly if someone paid me a competitive wage to do it. Or honestly even a bit under my normal expectation. Not every person wants to work on some ego-driven rewrite of a rewrite. Some people are fine working with legacy code.

Also there is a counter example right above my post. Someone was so motivated to work on it, they even forked it: https://github.com/X11Libre/xserver

Granted the fork seems weirdly ideologically motivated but anyway, case in point.