It would be nice if people could learn to think in terms of threats that fell somewhere between "safe to ignore" and "extinction level event". Or could distinguish between "extreme and expensive" responses and "effective" ones.
9/11 could have been prevented by simple, conservative and inexpensive countermeasures. After 9/11 politicians droned on about how "9/11 changed everything," but the cold sober fact was that it in fact changed nothing. It just showed that some of the things sensible people had already been telling us to do (like reinforcing cockpit doors or getting agencies to work together despite institutional rivalries) really did need to be done. Instead "9/11 changed everything" became the rallying cry for every pet scheme that had heretofore been correctly dismissed as too expensive, hare-brained, or just plain dumb.
Which doesn't change the fact that something needed to be done. Here's the lesson I think we should take into this infrastructure debate: we should take sensible and conservative steps to secure infrastructure against terrorism now, before events put foolish ones on the table.