Suppose that some pundit who has spent his whole career calling for bipartisanship, a compromise between the extremes of left and right, were to admit the plain fact that Obama is very much a centrist, who is in particular proposing deficit reduction through exactly the kind of mix of tax hikes and spending cuts "centrist" pundits demand — and that the GOP, by contrast, is an extremist organization whose extremism is almost solely responsible for the bitterness of the partisan divide. A pundit making that admission would in effect be saying that everything he has said and done for the past several years was not just useless but harmful, actively misleading readers about the state of the debate. He just can't do it.
The point is that a large part of the reason we're locked into such a mess is careerism. And yes, that's quite vile, if you think about it: politicians and pundits alike letting the world burn — probably unconsciously, but still — because their personal position would be hurt if they admitted to past mistakes.