It would be cool if Bungie took their own spin on this. I'm a huge fan of Mass Effect and Fallout, that being said I want Destiny to be it's own original vision. Morality definitely lends to replay value as you can go through the game multiple times, playing good, bad or indifferent. I also enjoy that it increases tension when you know your decisions affect the lives of those around you and how the game reacts to you from that point on based on your choice.