The exact same reason why Uncanny X-Men, Hulk, Moon Knight, Daredevil and Punisher all got #1s too. It's to boost sales. It certainly has nothing to do with the movies since these above books don't have movies out. Simple: marketing. Marvel is better at pushing their product than DC. DC simply isn't very good at advertising barring their handling of the reboot and Blackest Night. They are just not very fan savy. Remember their idea of a prize for fans was a stupid doughnut. Likewise mainstream notability simply does not translate into notability in the comics fandom. When a mainstream fan wants to get more of Batman, they aren't going to read the comic, they are going to watch the Nolan movies, watch the Batman cartoons and play the Arkham Asylum video game. Paying for the comic is at the very bottom of the list right next to watching the Adam West TV show.