Otherwise reasonably smart people who can't give up the idea that they are somehow "above the fray" has long been a tremendous frustration. I don't know how much it actually affects outcomes (maybe not much!), but it's certainly annoying.
Most of these people tend to be Democrats who don't want to admit they're Democrats. I don't care about partisan allegiance or loyalty, but we're talking about the kind of people (including many famous pundits) who regularly demand that Obama advocates for a position he has already advocated.
If you have vaguely liberal views on social issues and don't want the US to be a plutocracy, you're a Democrat whether you admit or not. Okay, fine, you can register for the Greens or declare yourself to be an independent or whatever tribal identification makes some amount of sense, but the Totebagger notion of technocratic centrism is a vote for plutocracy, not against. "Centrism" in DC is status quo+shifting wealth upwards.