I get the feeling that the real reason "progressives" are souring on Hillary Clinton comes down to the limits of cognitive dissonance.
Hillary is awkward and unconvincing. Sure, she's a bullshitter, but unlike Bill, she's not very good at it. Beyond that, it's pretty clear that the Clinton family is ridiculously corrupt - even if you argue that there's no laws they've technically broken, the wealth they've sucked in and the terms on which they've sucked it in is transparently foul.
But as president, Hillary would be the Pope of their religion. In fact, more than the Pope, because at least Catholics can regard the Pope as wrong on political or moral questions - but neither can be questioned by the progressive. The prospect of having to spend eight years pretending that Hillary is the champion of the poor and downtrodden, and a pristine moral example besides, has to be daunting.