I had a co-ed dorm room when I was in colllege (well. technically it was on weekends when my roomate was away...and there was a bit of subterfuge involved in not getting caught by the Resident Assistants..)
This look at Ms. Somebody or other that suports Co-Ed dorming is all I need to know: sophomore Jenna Davis sees it as a political issue. "We're very self-conscious about hegemonic gender norms," she said, referring to the assumption that heterosexuality is universal.
Having to live with her might turn me gay, or homicidal.
Back when I was a student (in the Dark Ages, naturally) the dorms were not popular at all, especially among independent self-supporting students like me who had a choice in the matter. You couldn't beat the location of a dorm, but it had its costs. Dorms were sometimes co-ed but had curfews if my recollection is correct, and they didn't seem to provide much space for the money - - plus residents had to vacate the dorms between terms, sometimes a PITA.
Often university students shared apartments with one another, instead. Nobody gave a hoot as to the gender of a roommate, as long as he paid his or her share and got along with everyone reasonably well. And with enough regularly paying roommates (who cares about gender? ), an apartment was much less expensive than a dorm.
I suppose that students are more prudish these days.