Petition against generic "thumbs-down"

I don't get negative reviews often, but I just got two from two different buyers within the hour. Both are generic "thumbs-down" ratings, and there was absolutely no indication as to why. It's a bit suspicious, but beside the point, the ratings are not even visible, yet they drag down my rating.

Has anyone else experienced problems with this? It's fine if buyers don't like what is delivered, but we deserve to know why.