Also you forgot to ask what might be the drawbacks of this change:
- moving windows could be less smooth: now it is the client which ask the server to move the window before it could be done entirely in the window manager.
- same thing with resizing window: there is a tradeoff between 'each frame is perfect' and 'smooth resizing' and I believe that Wayland went the 'each frame is perfect' way, so in some case the resizing may get jerky.
- it will take some time between an application crash and Wayland detects it, in the meantime the window will be unresponsive.
- if there is a new toolkit which provides only Wayland support, it won't have network transparency currently, it may get LAN transparency in the future (sending bitmaps of the window) but it is not sure that this will be usable for WAN: I believe that client side decoration increases the number of round trip between the server and the client.