I agree, some of the people who do that seem to have zillions of accounts and finding and banning them all would be a mission in itself. After all - you can't ban a person from owning a PS3 and accessing the online content. I guess it just leaves a nasty taste in my mouth when I'm trying to enjoy a game that used to have a good vibe to its online content.
But...
Perhaps the trophies that you earn online could be changed slightly. For instance, instead of earning the trophies through an average of your ratings, you earn the trophies from the total number of four star or five star ratings you received. That way, a million "accounts" could rate you a million times with one star but as long as the right number of people rated you five stars you would still achieve the trophy. Something like a trophy for "your video was rated five stars by one hundred people" and "your video was rated four stars by fifty people" or something along those lines. Similarly getting a video put onto the Hall of Fame could be done because it got the requisite number of five star ratings - regardless of the amount of one star bring downs it got.
I know, people could still cheat and gain the trophy by making multiple accounts and rating their own videos but it would not be in their interests to rate anyone elses with one star. Seeing as we already have trophies for the number of views you've had in a week, their actions would do nothing except give all the people they want to bring down millions of "views" of their media. And ultimately they lose out on the warm fuzzy glow gained with earning trophies through honest means.
There are probably flaws with this, but I would think in the long run, something along these lines would be preferable to an average score - and more achieveable (though still hard for the average player like me) because having your average being brought down by mean-spirited people would have no effect on it at all.
