I wouldn't say that computer RPGs ignore ethics. There have been a couple which payed close attention to ethics and reputation. Offhand, Darklands and Daggerfall come to mind. In the sci-fi genre, the Fallout games cold be a pain if you angered the wrong people.The problem is that designers don't want to box players in and make the game impossible if a certain NPC is killed. I can't say I disagree with that goal. In a tabletop RPG, the GM would have to do some fancy footwork to rearrange things after somthing catestrophic, but a computer can't do that. It has to have boundaries and only certain possibiltys are programmed in. I think the designers did a good job by incorporating the faction reputations the way they did.