Earlier quoted context omitted.
Clinton would have done the same. 9/11 was much different than the attacks in the 90s.
Clinton would have attacked Afghanistan, sure. But would he have stayed in Afghanistan and/or attacked Iraq? Those are the two items that have cost dearly.
The other reason was to create a local distraction. To keep "the terrorists" occupied, their violence and attacks confined to that part of the world, and not in the US. In that sense, they "fell for it" too.
If the public need for "revenge" had been satisfied by attacking Afghanistan, I think Clinton would have stopped there. He was not a risk-taker, and he was totally driven by polls.