No one will admit it, but I suspect at least part of the reason for grumbling in the Democratic ranks is that we're spoiled.
Iowa Democrats got used to seeing Barack and Hillary and The One We're Embarrassed To Mention Anymore every time we crossed the street, and we're a little jealous of the Republican activity. Sure, we have more Obama HQs than anyone in the GOP field, but that's just not the same as the real thing.
The lack of a personal presence has left Dems vulnerable to reporters seeking some story, any story, on the left to "balance" the bus tours and rallies of the Republicans. So they've fixated on the handfuls of uncommitteds and HQ Occupiers because hey, that looks like a story. They're more dramatic than the hundreds of Obama volunteers quietly making phone calls. (And for the participants, chanting Hey Hey Ho Ho Something Something's Got To Go with like-minded peers is probably more fun than doorknocking, too.)
Bill Clinton got this in 1996. He knew that Actually Being President is a bigger deal than Just Running For President, and did an Iowa fly around caucus weekend. We filled Carver Hawkeye Arena. And no, a video uplink on caucus night just doesn't cut it.
This isn't going to happen, but just for perspective: One 30 minute stop on the tarmac in Des Moines would completely eclipse the Occupy/uncommitted "story," and most of the Republican field as well.