While it might be easy to figure out who gave a negative reputation, I think the ability to see written negative comments would have been helpful. It would allow members to see why it is happening, especially if it is happening a lot to somebody like a new member.
Ignorance also seemed to be an issue. I noticed a few posts of people asking why they were being hit with the Unhelpful marking. Maybe just a sentence or two about how it is possible to have reputation reviewed and discussed on the top of the page where the given points are listed along with link to send a message.