Because the ends justify the means to communists. If we all could just be patient and see what the New World Socialist Order is like, we'll understand.
Clarice Feldman has a good piece on this up at American Spectator (here: http://www.americanthinker.com/blog/2006/12/dojs_democrat_line.html and makes a very good conclusion:
"A particularly telling detail was the bit in the news reports of Berger's treatment to the effect that DOJ sources insisted that "no original information" had been lost. That, of course, is simply the negative way of saying: All annotations to the original documents have been lost; we will never know for sure what the reactions of responsible members of the Clinton administration were to the contents of these highly important national security documents. Of course DOJ has always known this, as well as the significance of Berger's conduct So, what interest did the prosecutors have in minimizing the seriousness of Berger's crime--for crime it was, whatever the plea deal ultimately was? Or am I forgetting that the DOJ officials--the same ones who oversaw the start of Plamegate--have close ties to certain Democratic senators?"