Better screening is part of it, and a lot of it is students coming to universities already "diagnosed" with various mental health conditions and needing to continue their treatment. But, one particular article I read (and no, I can't remember the source) also noted an increase in students who experienced one or two of what I call normal bad things and then fall apart in some kind of depressive episode or extreme state of anxiety. These would be like the events you mentioned, such as a bad grade, a break up with a boy/girlfriend, a roommate problem. If you've never had to develop emotional coping skills because mom/dad took care of everything, these events are quite devastating. Some parents try to intervene with deans or members of the counseling department, even though their kids have not signed a release and they are over 18.
College counseling centers have changed quite a bit since we were in school. I interviewed at 3 universities for my second clinical internship; these are considered plum positions, but I was quite glad I didn't take the one that was offered to me, at MA College of Pharmacy and Allied Health. Just listening to the director describe the stress these kids are under made me cringe. A peer in my clinical supervision class did take that position, and the issues she dealt with were much more severe than what I had in a community mental health clinic, in a community with a lot of poverty. And then she had the school attorneys on her back about things like not letting her complete her transcription of 2 sessions for our class, until she relented to doing it on campus, which was a huge burden. I guess what I am trying to say is that they are dealing with some pretty complicated things now, and when they can't, they refer out and try to work with providers, to keep the kid in school.