Disenfranchisement is an ugly word, particularly for a party (and a state) that is still smarting from the disenfranchisement of its voters in 2000. When the Supreme Court decided honestly cast votes couldn't be counted, it was the most undemocratic move most of us have ever seen.
But the current Florida/Michigan debate isn't the same thing at all. The "primaries" in those states were held without the blessing of the party, and with the understanding by the candidates--including Clinton--that those states would not be counted. The states went ahead with their contests anyway, knowing they didn't count. The voters also knew they didn't count, so many people didn't bother coming out to vote. Why bother? It had already been established that they wouldn't count.
The attempt to change the rules after the fact, to make contests that were not meant to count into contests that would count, thereby disenfranchises all those potential voters who--following the party's rules--didn't bother voting in meaningless contests. Had they known the rules would be changed after the fact, many more would have turned out (there's a link in the TPM piece to a study backing this up). Their decision not to vote was legitimate, given what was known at the time--the Clinton's campaign to then seat delegates chosen by only a portion of the probable voters is what's not legitimate.
The DNC threw her a bone today, awarding her many more delegates than she should be getting, considering she had agreed with the idea that those contests would not count, and only changed her mind after she fell behind in delegates. If she indeed takes this fight to Denver, as she has threatened, she will only make herself look petty. It's not a noble cause, it's self-interest trying to masquerade as a noble cause, and that's worse than transparent self-interest, because it belittles genuinely noble causes.