The 9/11 and anthrax attacks were an attempt — very nearly successful — to entirely decapitate our government. Were it not for the fact that things didn't go 100% perfectly for the hijackers and anthrax attackers, we might well still be on our knees politically and economically today.
Think about it: Congress was in session that day. Most of the people serving there today were there then. The First Lady happened to be visiting Capitol Hill. Were it not for the genuine heros on Flight 93, that plane would have hit either the White House or, more likely, the Capitol Building (since it's easier to spot from the air). What the plane didn't get, the anthrax letters could have if that attack had been thought out a little better. In addition, it was just luck that the plane which hit the Pentagon struck a newly renovated, thus relatively unoccupied area, instead of the side of the building that houses the offices of the Defense Secretary and top brass (who were in the building that day).
We escaped the truly nightmare scenario of most of Congress, the First Lady, and most of the top Defense personnel being wiped out in one day, along with our airlines and stock markets. The concurrent anthrax attack shut down our postal service and could easily have killed hundreds, if not thousands more had those attacks been planned better.
Against this backdrop, if we have to have a 9/11 commission at all, it should be rigorously non-partisan, ethical, above reproach, and judicious. Instead, the clowns on that commision, Democrat and Republican alike, have severely let the country down. I, for one, will never trust anything they report.
dang good question and I just posed it to John Cornyn in a fax thanking him for having the courage to sign it.