Perhaps because they have other things to complain about? You surely remember FBI whistleblower Colleen Rowley. She really put the heat on the FBI higher ups, but they withstood her. And Dubya's administration showed where its heart was by giving one of them --- an official who had done a great deal to obstruct the inquiry into Zac Moussaoui's associates before Sept. 11th --- a special presidential award. Surely the Dems are raising the heat on that? Well, no --- I found out about it from a Paul Krugman column.
Republicans would not be so gentle. Republicans, while in a position of pure opposition, managed to make a fuss over completely inconsequential goings-on at the White House travel office. If Democrats are too moderate and genteel to complain about transparent corruption in places where it actually matters, what are they doing in politics?