I'm going with Georgia10's idea regarding Clinton's strategy:
I suspect that a lot of today's defiance on the Clinton camp's part is directly related to the fact that there are three more contests left, and promising to possibly appeal this decision is likely aimed at galvanizing her supporters in those states rather than taking the issue to the Credentials Committee.
The primaries always irritated me because my vote didn't count. This year my vote counted but it was just as frustrated as ever. For all I know, maybe Michigan and Florida are leading the way toward a solution with regard to the bigger picture -- bust up the rules to urge reform.
I searched back for Donna Brazile's op-ed about this:
Our nominating process is supposed to yield the best possible candidates for the most powerful position in the world. Unfortunately for all of us, it is a deeply flawed system in desperate need of reform. Recent proposals to create a regional rotation system in 2012, or the "Delaware Plan" to allow smaller states to go first, should be on the table for discussion starting this fall.