It seems like a big trend for Hollywood to make a movie, and if it's good, make two more to go with it. I know why most of Hollywood does it, is due to making money, that's all it comes down to. Look at The Hangover movies. The first one was hilarious and fresh, but the next two were exactly the same thing, except fun or fresh. I totally understand if it's super hero franchise like Batman or something like Star Wars, but movies like The Hangover don't really work well as a trilogy.
The same can be said about 21 Jump street and 22 Jump Street as it's going to become a trilogy with 23 jump street. The first two films are actually great, but a third can be anything.
Do you think Hollywood makes too many trilogies on pretty much everything? If Hollywood had control of every movie, I bet most of them would make trilogies. Imagine if Pulp Fiction went that route? Or scorsese did sequels to some of his hit movies, it wouldn't work right.