When I say that it's more of a fault of the site than the users, I mean that the review form have not encouraged constructive criticism at any point and despite that the current user base might not be entirely capable of writing such criticism, it might have been different if it had been there from let's say, the beginning.

As for an insightful review taking effort, I'd like to remark my point about appreciation again. My latest tileset did take something around fifteen to twenty work hours (drawing pixel by pixel rox !!), so I don't think asking for thorough criticism is too much. But then that is a user base problem.

So it might be the user base but also the site, I think it's a little bit of both.