Well, glad you asked.
1. Consider that prior to 9/11, the American public would not likely have supported a $200+ billion, full blown pre-emptive invasion of not only Afghanistan (al Qaeda training camps or not) but Iraq as well ("threat" of Weapons of Mass Destruction or not) and the resulting long-term occupation and reconstruction.
2. Consider the 1998 letters to President Clinton and GOP congressional leaders by the Project for the New American Century, the neo-conservative think tank founded by William Kristol in 1997 to press for an aggressive policy of Pax Americana around the world. Those letters called for the removal of Saddam Hussein's regime from power by any means (including force) and a shift toward a more assertive US presence in the Middle East. In a paper released just prior to the 2000 election, the group predicted that such a policy shift would come about slowly unless there was "some catastrophic and catalyzing event, like a new Pearl Harbor." Among the signers of the memos and active, founding members of PNAC: Donald Rumsfeld, Dick Cheney, Richard Perle, and Paul Wolfowitz.
3. Consider what has happened in our own country and in the Middle East since 9/11. Consider all the things (e.g., PATRIOT ACT, detaining people without cause or counsel, mission scope creep, etc.) which, prior to 9/11, would have been deemed unthinkable but whose questioning now is called un-American. Compare that to what the PNAC has been advocating since its inception. (See http://www.newamericancentury.org/iraqmiddleeast2000-1997.htm.)
In The Hitchhiker's Guide to the Galaxy by Douglas Adams, the ultimate answer to the question of Life, the Universe, and Everything is 41; unfortunately in all the confusion the exact question was lost. For the Brave New Warriors, the ultimate answer is 9/11; it's apparent they'd like to make sure any questions about it get lost as well.