The only time I've ever been intentionally loud during a movie in the theatre is when I went to a late showing with my friends and we were the only ones in there. It's common courtesy to shut the hell up in the theatre, and I strongly dislike people who fail at this (excluding during the previews. We're meant to comment on previews). If I have something to say, I whisper it.

As for going to the movies, I rarely do because of the cost. But if I can get in for free or if I really want to see the film right away or support the movie I'll go to the theatre.