The "good reason" is to rig the game.  That's not a good reason. The answer would be to not disenfranchise millions of voters, and not to rig the game with super delegates.  Super delegates might be helpful if someone dropped dead right before the election, or in the case of a virtual tie, but only about a third of them are elected officials, so that makes it even less valid.  So I stand by my no good reason claim.