This is the same kind of knee-jerk reaction that people jumped on over the school shootings - people kill people, games don't make people kill...
People (and I use the term loosely) who kill, maim and perform these despicable acts of violence are sick in the head, not from playing games, watching movies or reading books.
Religion is often the cause of these acts of terror, do we call to ban that ? No, and why ? Because that would be stupid. Think about it.