As most anyone here should know, I have no great love for the CIA. But in this case, they are the fall guys for the administration. The Office of Special Plans was created and staffed by neocons to further their agenda. They are responsible for most of the lies and misinformation, not the CIA. They (the CIA) actually tried to stop the lies and to provide solid intelligence, despite immense pressure to cherry-pick information and distort analysis.
In short, the CIA is blameless for the lies in the lead-up to the war, and they're taking the fall. Like a good soldier, George Tenet fell on his sword to protect high-ranking administration figures. Everyone can just have an easier time sleeping at night if they beieve lit was the CIA that ****ed up and made mistakes, instead of believeing that the people who are running the country lied through their teeth.
edit: damnit, I need a thesaurus.