As a non-US citizen, I can state that the irrational over-reaction was exactly the response that the terrorists were aiming for. Lots of Fear, Uncertainty and Doubt - lots of panic and mindless reaction... it has also greatly debilitated the effectiveness (and no doubt the profitability) of the entire world's air-transport system, without actually enhancing security thereby.

There is no deterrent here

IMO this would not in any way discourage future attackers - but encourage them.