If I am wandering lost in a raging blizzard, and I get cold, does it make any sense to douse myself all over with ice water? Judging by the actions of government employees the world over, but especially in DC, the answer must be "yes!"
Assuming that the "official version" of 9/11 is the true story, Atta and his fellow suicide murderers would be very pleased with the results of their "sacrifice". The US government was goaded into doing the bulk of the terrorists' work for them. The terrorists' plan succeeded more thoroughly than they could have hoped in their wildest delusions.
Their act was like opening a supercooled Coke and watching it freeze solid in fractions of a second. The US police state was beyond ready to "react", and was waiting for any excuse to crystallize. Any act would have sufficed, but that one was just too convenient.
The same could be said of the Boston Marathon bombers, whoever they might really be. Their terrorism was like a pinprick compared to the samurai sword stab wound immediately administered by the "law enforcers" who responded. I'm not saying the bombs weren't evil and didn't destroy many lives, I am saying that history will show the subsequent acts of State to be even more harmful in the long run.
The same goes for any and all of the mass-murdering "gun free zone" shooters. They are only a minor catalyst, and the State is the one who does the majority of the resulting harm, by proposing and enacting anti-gun "laws" which only disarm those inclined to obey "laws".
The right way to respond to terrorist attacks is to increase liberty- you know, that principle the terrorists supposedly hate so badly they are willing to kill and die to oppose. The right way to respond to massacres is to make it easier for more guns to be in the right hands and stop encouraging "gun free" killing zones.
The State always does the opposite of what should be done in these cases, which makes me think that prevention is NOT the goal.