User Reputation...

[Robbie Robb]

My guess would be that some people that are leaving negative rep do NOT understand that the rep is attached to a particular post and they were actually giving you neg. for a different post (or they just don't like you ). There's no way you should receive negative rep for simply agreeing with someone.

I gave one person rep on a post that it wasn't really intended for (although it was positive so it's not too big of a deal there).

I do agree, comments would be nice. I try to leave a comment for each one that I give so the person receiving it knows why I give it. I mean, if I'm taking the few seconds to give rep, what's a few more seconds to comment on it. If a person doesn't leave a comment because they are too busy or don't have time, maybe they shouldn't worry about the reputation anyway.

That said, I don't think forced comments would be a good idea however. As TP (I think it was him) mentioned - if you force them then all you'll get is "adj;askdjf" or whatever. The only option is to appeal to the moral decency of people (hehe - ME talking about morality...go figure) to leave comments.