The specific airlines whose glaring security vulnerabilities were exploited in the September 11th attacks should really be held financially accountable for gross negligence and reckless endangerment. The full financial implications to the American people of these airlines' negligence is phenomenal - we're talking hundreds of billions of dollars. So what does the government do? It offers to financially bail out the ailing airlines responsible for this costly negligence.
Without implementing strict security measures, these airlines not only pose an ongoing threat to the lives of thousands of Americans, but they pose a tremendous threat to the US economy as a whole. In the light of this, a choice not to fly could be seen not only as a very commonsense act of self-preservation, but also as a deliberate vote of no confidence in those companies that - in their current state of operations - pose a grave danger to the American people.
Do you really want to fly when the stated policy of the US Department of Defence is to shoot down any airliner that seems suspicious? Could an airliner be mistakenly considered suspect if something goes wrong with a navigational or communications system? Why even dare to fly in a plane in the wake of an amorphous terrorist threat warning issued by the Homeland Security?
Given the shoddy state of airline security, it's actually quite surprising that something this tragic didn't happen sooner. When you have massive airliners with unsecured flight decks, there's no telling what crazy crackpots might be inspired to attempt a hijack. Who's to say it even has to be a band of religious fundamentalist terrorists. Heck, some disgruntled and emotionally unstable layed off Oracle employee could decide to hijack a plane to fly it into the famous Oracle buildings.
So why fly, when the airlines don't care about your safety?