That's true, lacking confidence is less of a failure than confidently getting it wrong. But they weren't actually saying "we don't know". They were predicting a split election. Do pollsters even have a way to report that they lack enough confidence to give a prediction? I rarely see CIs on reported poll results so presumably they'd have to just refuse to publish any prediction at all, which clearly, they weren't doing.

Nate Silver has recently written about the clear problems in polling, and in particular the herd-like way they were reporting implausible numbers:

https://www.natesilver.net/p/theres-more-herding-in-swing-st...