Gamasutra article on morality on games

Ethics 101: Designing Morality in Games

"I think gamers get tired of doing the same thing over and over," says Pagliarulo. "We've slain dragons, beat up super villains, and shot at space marines over and over again. There's a level of burnout there. So when you throw in something like a morality system, it forces the player to stop running on autopilot, and think about their actions a bit more carefully. 'Shooting the bad guy' becomes 'shooting the guy who may or may not be bad,' and that in itself adds a unique twist to the gameplay.