People often base their decisions on the path of least resistance; that is, the path that causes the least discomfort for them. "Having to deal with morons hitting on them all day" is a discomfort that girls will probably have to deal with to some extent in any University no matter what course they are taking, but my argument is that it happens more often around people that have sex less often. And what do women in general (not necessarily the people actually taking the courses up) base their decisions to enter into a relationship with someone on? Lots of things. But one fairly large factor is their physical build of the other person; animal attraction. Being unfit is a sign of unbalance, so it's a healthy behavioural pattern for a species to naturally like the idea of sleeping with fitter people.
Picture a woman still unsure which course to take, sociology or computer science, visiting a university on its open day. Picking the crowd they will be associating with is an important part of their decision. Not to be sneezed at, either - if you find a crowd you to study with that you can build a synergy with, then the decision becomes quite respectable.
Taking up a martial art can often be the thing that kick starts an imbalanced person to do something about other faults in their life, too - most people will say that martial arts transformed their life, helped them restore missing balance. Other people take it up for 6 months and then give it up; usually because they have a crap teacher or it's an external martial style, and they simply started getting hurt too much (back to that discomfort issue).