Sorry, Nico, you use too much words and not in the clearest manner, at times it’s difficult to get the idea. And the post is going astray 
Well to the point, higher ratings and the more the better are saying to a potential buyer that the item is popular, many other people bought it, it’s safe to buy it. In many cases positive ratings will increase (not guarantee but just increase) possibility of purchase.
Moreover customers’ reviews are interesting to me in terms of author - customer relations, that’s why my initial interest was how to motivate clients to rate.
What concerns poor authors I meant your idea that (if I understood it right) gr authors are poor because they get smaller part of the money that they generate. Well it’s platform rules. They put resources, time, skills, envato gives a huge deal of exposure to items and authors, and I’m not saying it’s perfect platform, even your own platform won’t be perfect, just more customizable