@1993_toyota_camry@beehaw.org wrote a great post about Slashdot upvotes/moderation which I think makes a good feature request.

Here is the opening line of their post: "this was something I loved about slashdot moderation. When voting, people had to specify the reason for the vote. +1 funny, +1 insightful, +1 informative, -1 troll, -1 misleading, etc."

The post also mentions moderation as well so I suggest a full read.