A Psychiatrist Tries to Understand Angry Birds

Okay, this is my absolutely last Angry Birds post for this week. Dr. Dinah Miller is trying to figure out why people are hooked on this game. Help her out. While you're at it, maybe you could give me a clue. I liked Angry Birds fine when it was called Crush the Castle, and I like the art, but I've just never spent all that much time with it.