I hardly ever see comments used on questions, but having separate tabs for answers and comments really breaks up the interface for users, and I've had students complain about that being clunky. Either having both visible concurrently, or getting rid of comments on questions, would make a big difference. Almost all of the comments on questions end up being a way to get around the nesting limit for followups to answers, which is even worse, because it completely disrupts the conversational flow.