Disagree. The mantra here is 'apps before libraries'.
If the apps stand by themselves as parts of core, the library deps stand by themselves. If they don't, the libraries don't.
In essence, apps should be moved because of duplication of functionality/not required functionality. Not because of toolkit alone.
Otherwise, you'd get into the situation were "we moved this out because it used gtk1. Now it's ported to gtk2. Let's move it back!" Which is just plain weird.
Good points.
-sv