Or they're afraid of the slap-down they'll get for raising the issue.
Non-right wing news media are now so afraid of publicly discussing the issues that they let perfectly appropriate (and important) stories go by. They don't want to be another Dan Rather.
Fox News, and the right in general, have done such a good job in manipulating the social and media dynamic, that open discussion and "investigative journalism" has a bad name and is immediately attacked for being "anti-American" or Bush bashing.
Welcome to 1984... today.
Mr Mephisto