I don't see movies alone, atleast not in the theater alone but I am not a talker. I just enjoy someone elses company, plus I enjoy talking to them after the movie is over and discussing what we just saw.
The only reason for this is if it is a good movie I want to discuss it with someone and hear they did/didn't like about the movie. If someone hasn't seen the movie yet you do not want to spoil it for them. If it is a foriegn/independent/limited release chances of finding someone to discuss the movie with is pretty slim. Plus if it is a movie I really like and want to see I want to expose others who might not have heard of it or seen it to the said movie.