That's odd, I'm using Wayland on my desktop and, for example, Japanese input works 問題ない. Then again, I haven't tried every possible input method/peripheral in existence, so I may just be the one in [some arbitrary large number] who lucked out.

> Input is an afterthought

This. You need more than graphics to have a windowing system. Wayland team threw out X11, did graphics and left the rest for the others to figure out.