That's an interesting idea, but I don't think there's such a thing as an unbiased review. Well, biased isn't the right word for it, but different people will always have different opinions on how rating systems work. Having thought it through, changing the system probably isn't worth the effort it would take to swap all the reviews. But it's fun to think of some concepts, anyway.
One thing that would be interesting would be to take some older levels and re-review them. Standards have gone way up in the last 10 years or so, and some of the higher rated files on j2o simply aren't as good quality as ones below them. They're just older, from when people's standards were lower. Obviously there are files that deserve the rating just as much as before, but my point stands for a few of the levels, I think.