I am far from an expert on national security or airline safety, but let me speak as a concerned resident for a minute. What always strikes me after disasters or near-disasters is that new measures are announced that I suspect lots of smart people have been clamoring for for years. But they only happen after disaster strikes or almost strikes, so as to give the government "cover" to carry it out. E.g., "crisitunity".
After 9/11, Congress enacted legislation allowing pilots to carry firearms, and authorized more money on reinforced cockpit doors. After Richard Reid, you were encouraged to take off your shoes for screening. After the threat level went to "orange" in 2006, the screening became mandatory. After the latest attack, the government is requiring all travelers from 14 countries "of risk", including Nigeria, to be subject to full-body patdowns, and added dozens of names to its watch list.
What strikes me is that each of these measures only came after a threat, and sometimes it seems that many more measures are on the "wish list" for those who perhaps call for more stringent measures for airline security, but are now deemed to be too politically volatile or would engender too much public opposition. Case in point is the new scanner that would reveal what's on your person, anatomically disguised, which has received opposition from civil liberties advocates. It's probably deemed a bit "too far" for some and so it will take another attack or near-attack for it to be fully implemented. How many other measures are out there that will only be implemented after something goes wrong?
Now, that doesn't mean every item on every airline security "expert's" wish list should be implemented- no doubt there are some radical ones out there, such as internal physical examinations after a terrorist in Saudi Arabia successfully stored a pound of explosives up his rectum in an assassination attempt on a prince last August. And none of these measures provide 100% protection against an attack. But given the trend, it does give me pause that perhaps there are some things not being done that should be, and Americans are forced to wait for crisitunity to become safer.
Update: Here's an interview with former 9/11 Commission Chairman Tom Kean Sr. re how the attempted attack "probably did us a favor" re failures in the system (h/t Jason Springer):
Embedded video from CNN Video