Which in this year makes them truly super - as in superfluous - if they are not going to exercise independent judgement. Their purpose for existence is to stand up to BTD, for example, if it means a clearly better shot at winning the election.

Well, the DNC did protect their primacy. After MI and FLA (and SC and Nev) moved their primaries up, the DNC decided to allow SC and Nev to do so, and disallow MI and FLA (because somehow SC and Nev would allow African-Americans and Latinos more of a voice in the early primaries, but MI and FLA wouldn't).  And then NH and IA, not satisfied with the DNC's actions, moved up their contests even earlier, and the DNC allowed this.

Once NH and IA were allowed to move their primaries up still further, making them the very first contests no matter what, any rationale for disallowing all of the MI and FLA votes disappeared.  Nevertheless, the DNC stuck to its guns, even though the ROOLz provided for a far less draconian punishment: giving each delegate chosen in the primaries a 1/2 vote (instead of zero votes).  

Having imposed a penalty in excess of that provided in the ROOLz, the DNC arguably forfeited its claim to the moral high ground, especially since NH and IA ended up first no matter what. The ROOLz do not require, or even encourage,  SD's to vote either for the holder of the most pledged delegates, or the candidate who won their respective states (Kennedy and Kerry for Clinton, anyone?).  The ROOLz permit SD's to vote for whomever they please, for whatever reason they choose. You can argue about what those reasons ought to be, but none are excluded by the ROOLz.

If it had been intended for the pledged delegates to merely anoint the pledged delegate leader as the nominee, there would be no need for SDs -- all delegates would be pledged, and on or the other of our two remaining candidates would almost necessarily end up with a majority of them. However, because (as the "legislative" history shows) the SD's were created to act as a counterbalance to the pledged delegates if appropriate, they can consider any factor not excluded by the ROOLz, including the results of polls, results of late primaries, results of "disallowed" primaries, perceived "electability" issues, etc.  

Ever since the current primary-dominated era of nominations began in the 1970s, every Democratic and Republican nomination has gone to the candidate who received the most votes in the presidential primaries.

How many superdelegates want civil war? Will igniting an intra-party civil war make Ms. Clinton electable?

It is what Sartre described as "bad faith" to posit  Ms. Clinton a stronger general election candidate while ignoring what a superdelegate-override that nominated her would do to the political environment in which she'd be running.

If Obama is ahead in popular votes and pledged delegates come convention time, and if the superdelegates handed the nomination to Clinton in the absence of some kind of Obama "incapacity" (dead girl live boy), how do you think African Americans and many of Obama's other supporters would react?

It would make Hubert Humphrey's 1968 nomination in Chicago look like a cake walk.