PG-13 movies might be considered too raunchy for 13 year olds. Twenty years ago there would not be sex and drugs in a PG-13 movie, but today, PG-13 movies are filled with sex, drugs, nudity and profanity.
Some people will choose to go to a movie if a certain actor or actress is starring in it. For example, if Zac Efron is starring in a movie, people will be more likely to see the movie than if a 'no-namer' is starring in it.
Movies play a big role in social media in today's world. For example, after a movie is out, people create memes all over twitter. People tend to state their opinions based on celebrities actions.