Personally I'd leave it as it is, the galleries are just a place where people can share images. There is no 'prize' in getting straight 5's just like there should be no penalty for getting straight 1's. Any rating system be it out of 10 or 100 or 1000 will have the 'people rate too high' aspect because by our very nature we do not want to hurt people's feelings. If you must make a change, strip the ratings altogether and merely have comments, that way people can say 'yeah, cool, but it could use....' My two pennies worth.