What's with Movie Titles lately?

This isn't a new phenomenon but seems to be getting more common. Movie titles that seem to have no connection to or explanation from the film. Here's a few recent examples.

Cloverfield- There is a mention of the cloverfield in a title card but it's not really explained where it comes from.

Before The Devil Knows You're Dead- an apt title for the film but as far as I could tell was never referenced in the film.

Persepolis- A quick Google tells me that Persepolis is the name of a city in the Persian Empire and now in Iran. That's never explained in the movie, it is kinda a cool title though.

I Am Legend- Maybe it's the title of the book the Will Smith movie is based on but it doesn't make a lot of sense. Perhaps they are referring to the status of his character after the events of the film.