The point above, and similar to what Jason_V wrote, was the main reason that for many years, I went to the movies once a week, every week, with my friends. Oh boy did I see some absolute trash that way. And while I'd like to think it was just an excuse to socialize, in reality there's little chance to socialize when you're sitting quietly in a darkened theater with everyone staring at the screen. So we'd actually catch up for maybe 30 minutes all up during the night, the rest of which was taken up by the latest brain-cell-destroying blockbuster, and/or getting drunk at the pub.
Well, yes. We don't sit there and talk through the movie. In fact, the minute the lights go down for the trailers, we shut up. The socializing comes from from the pre- and post-show. When we go get lunch, do some shopping and make an entire day of it. Way back in the day, I went to the movies every week by myself. While I'm content to go alone, I wanted to share that with someone else. It's the shared experience-maybe I should have used that as the more specific reason.
Going to the movies with the group is a great lesson in compromise. I never wanted to see A Good Day to Die Hard, but since my friend did, we went. We both thought it was terrible...and he made it up to me by going to see Jack the Giant Slayer with me. And, alas, that was terrible too.
However, we have a good laugh that our first movie together last summer was Magic Mike.