A Question For Those Protesting the DNC Decision

In my former life I was in politics and political circles so I’m asking this out of genuine curiosity.

As I understand this, both Florida and Michigan had people on the Rules and Bylaws committee that helped make up the rules that were being appealed today, so nobody can say that the rules were not known.

The rule was that if a state moved up the date of its primary (to January) after the four states that were chosen to go in January were chosen, then that state was going to lose the right to have their delegation fully seated. The states that were chosen were NH, Iowa, NV and SC.  Michigan and Florida moved up their dates to January.

My question: why were Michigan and Florida surprised that the DNC was enforcing their rules? And why should the delegations have been seated at all?

Like I said, this is out of curiosity.