The really funny thing about using 9/11 as a reason not to fly is that by the numbers, you're far more likely to die from a terrorist attack sitting at your desk than on a plane.
Of course there is the control factor. A lot of people are more comfortable with death (everybody does eventually) than they are in letting others have control over their lives. Perfectly understandable in a society that promotes and values individualism.
For me, the aversion to flying is mostly rooted in the invasiveness of being searched, the hassle of sorting and packing, limited amount of gear I can bring, and the time it takes to get to the airport and through security.
Unfortunately, the profession I chose has required that I travel by air. Anything more than a 10-12 hour drive and I have to get on a damned plane.