I don't know about others, but personally I like to be the one in control of my desktop, not the window manager. Hildon forces me to run applications fullscreen, whether I like that or not; Hildon doesn't allow me to (easily) change desktop fonts or eyecandy; Hildon is, as Sean Luke pointed out, in various places quite un-ergonomically set up, but I can't change that. Maybe, but KDE is flexible. It wouldn't be that difficult to make it nicer and there are tons of skins out there that give you the window widgets you like. You'd think, but -- no.