In the Mass Effect games, the moral choices you make a really important.
You should be able to gain points in either side that can be used to power up social interaction. Having a reputation as a particular sort of person can come in useful – and it should also be used very occasoinally against a player.
Example: A character takes a penalty to Persuade in diplomatic situations if they have a high Renegade score.
Example: A character trying to Intimidate takes a penalty if they have a high Paragon score.