I think people should just play how they want to play and deal with the consequences
If you get a bad rep and no-one trusts you, the counter side to that is that your being cutthroat probably gave you a lot of advantage over someone who was more long-sighted about his alliances.
There is an advantage and a disadvantage to being cutthroat. I think that works out just fine, instead of trying to make everyone play the same way.
- Kel