I believe we are a forgetful people. We haven't had a major attack in the US since 9/11 so people lose their resolve. After 9/11 everyone spoke of tough defensive and offensive tactics to take to prevent this from ever happening again. No one minded waiting in line two hours to go through security checks at the airport, etc.
Now, we are all about the inconvenience that it is causing. Also we are worried about civil liberties being infringed upon by ID checks, etc. I think the people in NY and probably other parts of the US and the world as well, are not as willing to bear the financial burden which would be required to truly be as secure and prepared as possible.
I listen to a conservative radio talk show occasionally and the host predicted this would happen. He made his prediction within days of the attacks. It is just human nature, in my opinion. We can't worry about everything so we concern ourselves with whatever issues are most pressing to us at the time.