I think the democratic party is upset that everyone wasn't going along with the superdelegates who really have the first votes. They want to choose their candidate and go through the motions of a primary.
The one thing the Iowa caucus did was make it easier for grassroots candidates. If they hadn't bungled the caucus so badly in 2020 for example, Pete Buttigieg would have had a better shot at it like Obama in '08 (he won the caucus, but we didn't find out for weeks!).