Seems that GD is now accepting UI questions.
"there are very distinct professions for UX experts and graphic designers"
While that's true, the best UX and GD folks I've worked with (in terms of interactive) are the folks that overlap the two disciplines.
I'm find with them being different SE sites, but not if both open up the discussions to both. That just leads to confusion and crossposting hell.
To add to it, perhaps I'd summarize it as:
It'd make sense to merge the two sites, or keep them separate. It does not make sense for the two sites to be duplicating content and competing for the same type of user.
I'm interested in GD. I'm interested in UX. I frequent both sites every day. If I have a UX question, I now need to pick one or the other or spam both. Seems like a bad idea.