I don't think I agree that John Edwards' "inability to get any substantive purchase in the national press has a lot to do with the very nature of [his] positions." So far as I can tell, the only (positive) coverage Edwards gets in the press comes from his poverty focus, health care plan, or general reformism. These positions, which many in the media agree with, are gradually being overwhelmed by the fact that he's stagnating or dropping in national polls and has lost his once commanding lead in Iowa, which makes him look like an increasingly fading presence. None of this explains why the haircut stuff has gotten so much play, but I'd actually chalk that up not to the media have a substantive problem with his dislike of insurance companies, but with the media being awful, and all-too-easily led around by the right wing noise machine. Which is, in some ways, worse.
The funny thing is, this is probably Edwards' best hope. If the media writes him off beforehand, that's better for his campaign, as the media tends to believe its own storylines. If he really can win Iowa, it's crucial that it doesn't look like he will win Iowa. Otherwise, his win will have no bounce. And while I'm increasingly pessimistic on Edwards' chances, this speech could well become the "Two Americas" of this campaign.