it did motivate me to rate the game I'd played many times. It's not a 10, but waay not a 1.0
I would figure if you rate something a 10 you would probably want to back it up with some words, not just a sentence saying 'best/worst pin ever nuff said'. Maybe on the ratings you could have a stipulation that pops up in the formatting, 'you have rated this machine the top/bottom score of all time, in 80 words or more, describe what makes it so great/terrible'.
Personally I think its silly as its all just speculative, but also I'm a certified beer judge, and I see where ratings are necessary for things.
At the same time, the best beer or pin in the world may not be the greatest ever to others. Ultimately it'll all come out in the wash. In the meantime, if you want ac/dc to be the best pin in the world, then today is your lucky day if pinside is all you use to dictate your decisions.