It's sometimes seemed a bit inelegant to me that that using the conclusion in the premise is automatically invalid. Why is this? It seems like a special case.
Actually it's not that there's a special case against using the conclusion in the premise, it's that the point of argument is to show that the opposing position is irrational, and the opposing position is only irrational if information available to the person who holds it contradicts it. So I wish people wouldn't talk about "circular reasoning" but "disputed premise", because that's the more general form of the fallacy. I think talking about it as if this fallacy is limited to using the conclusion in the premise of an argument for the same conclusion opens a door to people making arguments that take other disputed premises for granted, and claiming it's not circular reasoning because the conclusion isn't in the premise (a different disputed claim is).