The caucus vote is not secret; many people including myself would not attend. Votes in some states were limited to a few hours, inconvenient for many people.
It some of the Texas caucus sites, voters were lined up, one line Obama, the other Clinton. The boss could be in one line, the employee in the other- the objection to this is obvious! The same is true of the so-called 'town meeting' caucuses in a state like Maine; the blue collar worker or farmer will not attend.
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Many millions were spent to hold the primaries by the states of Michigan and Florida. They are not going to duplicate that expenditure to hold repeats. In some cases, the voting machines were on rental and may not be available at a convenient time.

If the primary voters are short-changed by Dean and the Democrat wiseguys, many angry voters will not vote in the election or will shift their vote to the other party.
In a close election, this could be disastrous for the Democrats.