When someone says "7/10", what do they mean? It could be "it's pretty good but not spectacular" or "it's barely usable but I've seen much, much worse". I agree that we need a new system.
I forgot where I heard it, but I remember a game journalist saying that they preferred 7/10 games to 10/10 games. And I just wanted to scream at them. "Then fix how you rate games!"