There are still many ways for terrorist to attack civilians on commercial aircraft as well as in airports. The recent bombings in France and unexplained crashes in the Middle East are examples of how security is lacking. Operation Yellow Ribbon was the Canadian response to help the U.S during the grounding of our flights on 9/11. We need worldwide cooperation in the effort to improve airline security.
Since 9/11 the security, although much tighter, has become a pest. The agents are continually getting into trouble, scams, drama, and shaming at its finest. Personally, I started only flying first class, or privately (depending on airports and destinations) so that I can skip past the malignant abuse. Give someone untrained a badge, and suddenly they are throwing power around like Zeus. There have been more problems with the actual security staff, than there has been with any catastrophes. Seriously, take a look at the articles some time. The body scanners are ridiculous as well, I have seen first hand, guards taking photos of the screens, and seeing others and laughing or, pointing out things and snickering. Its like they are all stuck in middle school mentalities.
Airport security has gotten tougher, sure. But we lost a great deal of liberties that day, and it has made flying nearly immpossible for many people that day. The 9/11 attacks were a fluke, not an explotation of a flaw in the security of airlines. It might be just as likely to happen today.
The TSA does internal quality control tests, and journalists do these tests as well. The tests show that TSA agents do a very poor job of inspecting luggage for problems and dangers. It doesn't do the public any good to make me take off my shoes. It is busy work to give the appearance that we are safe, when we are not safe.