There are two main reasons why investigating and, if necessary prosecuting members of the Bush Administration. First, we need to ask ourselves what kind of nation we are. Are we a nation of laws, a nation that works with other nations to foster justice and democracy around the world? Or are we an empire whose maintenance justifies any action?
Second, If we decide that things like torture and the elimination of basic civil liberties are acceptable for the President to use, do we draw a new line that the President can't cross or do we leave the door open for a dictatorship down the road?
We know that the USA under Bush committed war crimes. Bush admitted it. Cheney admitted it. CIA Director Michael Hayden admitted it. Books have been written about it.
Cheney in recent interviews has been not only unrepentant, his admissions are essentially daring Congress to go after him. Cheney is betting that they won't. This will establish a precedent that future Presidents who want unlimited power can hide behind.
Some congresspeople like John Conyers want to investigate. The media, who were on the bandwagon all along, naturally wish it would all go away.
Obama and the Democrats had an epic win. Republicans are arguing amongst themselves and Karl Rove's Permanent Majority is rubble. But these people are like weeds that can't be killed. They never give up. Just like Cheney and Rumsfeld learned at Nixon's knee, loyal young Bush stormtroopers, like this guy, will wait, and have their time again.