You really don't get it, do you? Wayland is not allowing to bypass the WM for window decorations, Wayland is enforcing it. Under X11 an application has to explicitly override getting the window decoration used by the WM. Under Wayland applications have do it all by themselves. That means that even though one DE’s interface guidelines demand uniformity among them, and I repeat this the third time now, KDE applications will have one window decoration and GNOME applications will have their own and considering GNOME’s currently set work flow, all GNOME applications may not have a 'Minimize' button. Applications not belonging to either group, such as Firefox and Chrome (the latter doing it already by default but with an option to use WM decorations), will have to implement decorations completely on their own.
Behold the (possible) future of Linux applications:
http://imageshack.us/f/145/31341369.png/ (Just an image I gimped up in a hurry.)
Yeah, after years of working on consistency (such as the fd.o icon naming convention which allows one icon theme to be used by both KDE and GTK applications) the element that was consistent even in the most inconsistent times of Unix GUI applications, the common window decoration by default for all apps is thrown out the window.
It'll be a usability mess if uphold and all because of some Inkscape users…