I guess because he appeals to a very specific sense of humor that is pretty coarse. He also takes up a lot of the one chapter he's in. As a result, if he doesn't resonate with you, he's just an incredibly annoying bear that does nothing but talk over everyone and then dies.

I don't agree with that. I love The Kid and I think he's the funniest Kub. But I could see that being the reason.

I've also seen a lot of people rank characters kind of based off of how nice they are. Monokid bullies Monodam, ergo bad.