To have a point based feedback system, it requires input from gamers themselves, this arises two problems:
1) How are we sure people will even bother voting? I know i wouldn\'t
2) Abuse of a voting system. People may vote negativly of someone, even though they were nice (like say they were offering a fair price on an item, and even tried to cut a deal with you...but they wouldnt give it away for free), or they can vote negatively at random (just walk up to someone and vote them negative for no reason at all). Or Someone could vote positivly on someone to make their \"Evil\" rating go down, whether it be for competition reasons or no reason at all.
Basicly what it comes down to is, to ensure that the entire system works flawlessly, you would have to do a ton of work, and when it comes down to it the system wouldn\'t be any better than a simple word of mouth system. Your reputation should be based on your actions toward others, not whether or not a player clicks a button that says \"This guy is cool\".