One major reason for me is the lack of courtesy from fellow moviegoers, especially with phones. A bright smartphone screen in front of you is jarring, especially in a dark theatre, and especially with 3D movies. I've even seen people take phone calls in the theatre.
Stadium seating solves this problem as the gradient usually hides phones in front of you. I have started to either sit in the front row balcony, or stadium seating, or just refuse to go to theatres.