ok, so i used to wear my grado sr80's on campus and on the shuttle to campus. i loved them and didnt care what other people thought.
i recently wore my new sr325i's to campus and felt a little more awkward since they are bigger, flashier, and lose a lot of detail from outside noise (which totally kills the purpose of wearing more expensive headphones)
so, i ordered some cheap-ish iem's to wear to campus and in the library, but i'm still gonna wear the 325i's when i'll be on campus chilling outside for longer periods of time.
however, i still don't think there's anything wrong with wearing full-size headphones in public. as long as they're not overly huge (usually not the case) then it's fine. of course closed headphones make them more practical.
a lot of you say that it's social suicide to wear full-size headphones in public... my guess is that the majority of you are probably still in high school. when you get older, you'll realize that it doesn't matter