Super Delegates ha! Call them what they REALLY are: Crony Delegates!
Actually the reason they have them is to avoid a deadlocked convention. I think it was after 1968. The idea is to have a large block of people who put the party above any one candidate who can decide a deadlock without going 20-30 ballots. Of course also serving the purpose of tamping down an insurgent candidacy, but mainly to prevent a deadlocked convention which is widely assumed to be harmful to any winning candidate.