slackerboy
Super Freak
I remember seeing Star Trek Generations in the Savoy back in 1994 and everyone clapped at the end - I was taken aback by that, I'd never encountered it before. I can't recall any specific examples of people clapping in the cinema since then. Like you I find it a little weird and it would infuriate me if it were all going on during the actual film.
It happens a lot with older movies. The Summer movie series at the Ohio Theater in downtown Columbus plays a lot of classic films and the crowd there usually applauds at the end. Can't say I've noticed it with new releases. I would've been taken aback too 'cause Generations wasn't very good.