That's kind of how Slashdot used to work: you couldn't just up/down vote, you had to pick a reason why, from a list. "Insightful", "Funny", "Informative", etc. for upvotes, "Incorrect", "Trolling", "Off topic", etc. for downvotes. Of course, Slashdot also had meta moderation, where you could occasionally be given the job of up/downvoting other peoples' votes, which in turn influenced how often they would be allowed to vote in the future.