I was just reading that article in Poynter, it said:
Much that is commonly "understood" among journalists is rarely voiced in public. A pre-convention event this week in Cambridge -- where network anchors went on the record about the partisan and corporate pressures they feel -- was a bracing exception. The Shorenstein Center program was mostly noted in the news for Jim Lehrer's chastisement of the big three anchors for their stinted convention coverage. But even rarer was the theme kicked off by Dan Rather at the start: "Fear has increased in every newsroom in America." The three anchors (Rather, Peter Jennings, and Tom Brokaw) sparred with one another about whether it was "fear," "caution," or "anxiety," but its existence seemed clear.
Rather started by noting this: When you're a reporter contrasting what someone in the administration says with what you know to be the facts, pointedly laying out the differences, "You're gonna catch hell." "And those who are willing to pay the price," Rather said, are fewer today than before. In a later remark, he said the strong feelings nationwide and the guarantee that they'll be voiced not only calls up more caution than ever -- sometimes a good thing -- but causes some to ask: "You know what? We run this story, we're asking for trouble. Why do it?"http://www.poynter.org/column.asp?id=54&aid=69110So it appears they are being cowed by their corporate offices.