A party in power must have legitimacy in the eyes of the voters if it is to act. In order to perform its role, the party must achieve sustained electoral success over time and across geographic regions. It must be able to speak credibly as being authorized by the majority of citizens to enact policies, promote programs, draw up legislation, staff bureaucracies, and utilize public funds in ways that a significant minority of the population does not like. Legitimacy, and thus the authority to take action in the name of the public, must have formal grounds (all procedures have been followed) but it requires something more and somewhat ephemeral - the perception that the procedures were performed correctly and that the outcome is valid. While office can be taken on purely formal grounds, the lack of a consensus that the procedures are valid will obviate legitimacy.
In the current Democratic primary, the campaign fails on both formal and perceptual grounds. The exclusion of Michigan and Florida votes from the candidate vote counts is not legitimate because the rules allow remedies, including revotes, and because one candidate will not participate in attempts to remedy the situation. Thus, growing numbers of voters, particularly those in the disenfranchised states, are protesting that they will not accept as legitimate any nomination that excludes these states' votes.
Whether you support Hillary or Obama, the legitimacy of the Democratic presidential nominee as such is in grave danger:
- Opinion polls consistently show that the public regards the popular vote as the most legitimate measure of a candidate's victory. You win the vote, you win the election.
- Super Delegate votes are no longer sufficient to decide this contest.
- Obama and Clinton must meet the same two conditions: they must present themselves for judgment by the voters of Michigan and Florida and they must secure the popular vote. Hillary has met the former condition. Obama may have met the latter condition, but only through explicit exclusion of almost 10% of all primary voters.
- Should either fail to meet both conditions, even should that person secure the formal nomination, that nominee will not be regarded as legitimate by a significant portion of the electorate, both Democratic and non-Democratic. Thus, just getting the super delegates isn't enough.
- Clinton cannot win enough popular votes (barring some enormous upsets in the upcoming primaries) without Michigan and Florida to secure the nomination. Thus, she has every incentive to promote a resolution that is both in her favor and satifies legitimacy requirements.
- Obama is ahead in popular votes at present, but holds a statistically significant lead only because the vote counts from Michigan and Florida are not included. Despite having a lead in popular votes, he will not be seen as the legitimate nominee unless Michigan and Florida votes are counted/revoted and recounted. He is in a bind because the resolution that would ensure his legitimacy may also result in his defeat if the majority of voters do not choose him.
It is by no means certain that even if Hillary could secure the votes of Florida and Michigan and do so with their current vote distribution she would win the nomination. It is certain that Obama's nomination will be rejected as illegitimate unless he accepts the judgment of Florida and Michigan voters on whether he should be the nominee. To repeat, at this point neither of them can be a legitimate nominee on super delegate votes alone.
Arguing the rules does you no good in the general election if the outcome of adherence to those rules is rejection by the voters.
Updated - In response to CognitiveDissonance in the comments - Even if Hillary drops out, Obama has not met the conditions for legitimacy. When he refused to agree to a revote which would have remedied the situation, that is when he put himself in opposition to the voters of those states. If he "wins" the nomination by forcing her out before those states are counted, he loses the general. In short, Obama has dealt himself a nearly unwinnable hand. At the same time, the only winning strategy for Hillary is to pursue a revote and to decisively win them by at least the margin she won the first time around.