I don't know. In normal interactions, I get the impression that the reasons for positive responses are a lot more honest than the reasons for negative ones -- e.g. "I already have plans," rather than "You smell like bark. All the time."
It would be helpful to know why people mod us down, but it might just make people bitter.
Well, explaining why you thought a point was wrong is a little different than trying to hide dislike or indifference towards a person. The former isn't personal.
The problem with explaining every down mod is that it causes a whole discussion to occur regarding moderation. To me, that seems like a tremendous waste of time.
In a democracy, not everyone is going to see things in the same light. That's just something that we all have to deal with and move on.
It would be helpful to know why people mod us down, but it might just make people bitter.