There's nothing wrong witht the current rating system. It's an opinion based evaluation of pins based on a pretty good set of criteria. What you end up with a list where very little separates pins within 20 places of each other. Over time, with lots of ratings, pins find their level.

The problem is people make too much of the relative positions, as if there is significant difference between #5 and # 15.

You would but there are many who would say that Metallica is better. In the long run, with hundreds of ratings, they are pretty close. My point is that the current system works over time and games level out likely where they belong. Just don't make to much of the rankings because its opinion not fact.