exactly. i'm always surprised in looking at my rep to find which of my views struck a chord with others and which others were completely ignored (like this post will be). like bungadiri said, it's just another level of communication. it's another way to decipher what people are thinking out there, what their views are, etc. it's best hidden, b/c then it doesn't turn into a show-and-tell or popularity contest. there's no inherent benefit to giving or receiving rep.
That can also be used as a stalking tool for people who want to harass other posters. When you get neg repped three consecuitve times within about 8 days by the same poster sending angry messages it gets really tiresome. Agree 100%