Well imagine a Mass Effect type game where the random thugs from gangs you fight are not faceless, they are all NPCs who live in the world and you may have met and talked to. There may even be some of them that you like, it would give players a real reason to try and talk their way out of trouble instead of killing everyone.

Or imagine a Grand Theft Auto game where the random NPCs may live or have family and friends on the same street you do and you can talk to them. Imagine how much more alive it would feel if you could see the friends and family of people you killed upset over. Or if you kill too many people and don't make friends your safe house will not remain safe and people may decide to attack your character while he is taking a shower or something. That would add a whole new level to the game play of games like this if you ask me.

Maybe I am the only one who wants this but it is the feature I know I would most like to see in future games.