I hope this hasn't been said a million times before, because I don't mean to pressure anyone. I'm not a wayland contributor.
I just wanted to say that Wayland should really consider letting windows get/set their positions. The main reasons are that apps such as popups and dialogs are usually supposed to start either at the center of the screen or the center of their parent app, and that apps often want to remember where they were when they closed so they can open there again. Could something like this ever be added?