So, why Catwoman?

I know it's something nice and extra for the fans, and in the context of Batman: Arkham City's story, I'm all for Catwoman, but why? Why include just about every Batman character ever this time around?

Dax Ginn, marketing game manager for Rocksteady, told me that players nowadays don't always want to be the good guy. "It's not always fun being the righteous arm of justice, so we wanted to explore what it was like to be a criminal within Arkham City, as well. Catwoman became a great option to explore that."

But maybe it's simpler than that. "We kind of look around at other games," Ginn said, "and it's obvious that some players like breaking the rules."