Hell, the airplane-as-missile strat didn’t even last the full day of 9/11.
As soon as a hijacking stopped meaning a free vacation in a tropical, non-extradition country, and started meaning "you're going to die if they get past you", there was a powerful incentive to oppose it instead of sit back and wait for the stewardesses to come past with the drink cart.
It was a one-time-use tactic, and changing airports completely as a reaction was a huge waste.
As soon as a hijacking stopped meaning a free vacation in a tropical, non-extradition country, and started meaning "you're going to die if they get past you", there was a powerful incentive to oppose it instead of sit back and wait for the stewardesses to come past with the drink cart.
It was a one-time-use tactic, and changing airports completely as a reaction was a huge waste.