Sorry, Baume, but you conveniently left off an important part of the history of superdelegates and primaries.
If that seems a little undemocratic, that's because it's supposed to be. The Democrats created superdelegates back in the 70s and 80s after voters lined up behind some particularly unsuccessful candidates. Party bosses decided they knew better than voters, so they created a system whereby the governors, senators, and various luminaries got to pick their candidate independent of voters.
Um... That's only part of the story. Up until 1968, the ONLY people selecting the party's candidate were party delegates. Or, put another way, 100% of the delegates were what we now call superdelegates. After the '68 riots in Chicago, the DNC created the primary/caucus system. THEN, after a lackluster 70s, they decided to give a small amount of power back to the party establishment. Today, it's only slightly less than 15%. So, it's only been for two nomination cycles in the history of our country ('72 and '76; '80 was an incumbent year) that voters had 100% of the power in choice of candidate.
BUT! More importantly, there is no requirement at all for a candidate to be selected democratically. None. Because this is not an election. It's the party's process for choosing a candidate for an election. Hell, if they wanted, the DNC could choose their candidate by drawing straws or arm wrestling or picking 1000 people off of the street to play the world's largest game of pin the tail on the donkey.
With today's process, the people have more say in candidate selection that at almost any time in our 228-year history (we're talking Constitution here, not Declaration).
And, finally, as others have pointed out, if by some miracle Bernie started sweeping states and dominating the primaries, the superdelegates would certainly vote for him at the convention in a show of party unity. That's why conventions are no fun anymore.