Of course the social experience of the cinema has little to nothing to do with talking. It's about a shared experience. There's an energy. When the whole audience is really "with" the movie, you can feel the vibe. It's exciting. It's fun.
While it may not have the same interactivity or intimacy as a night of live theatre, it's still a communal experience. THAT'S what people are applauding. Their shared appreciation of what they just watched.
I love going to midnight showings, just for that. Everyone's excited. There's an anticipation. (Presumably they wouldn't be there at midnight if there wasn't some measure of optimism about what they were about to watch.)
That's why it's so upsetting for me when someone ruins that by being inconsiderate.
Went to the movies with my wife the other day, and I was shocked that someone in front of me had turned on their iphone during the movie. I leaned over and was even more shocked when I realized it was an 80+ year old woman. I've been in Florida just over two years, I should be used to it, but it just gives a new perspective when people complain about "kids" on their cell phones.
(My wife pointed out to me that it wasn't just that woman. The entire row -- a single party I think -- was checking their phones the entire time.)