Perhaps Americans have been making too much of these guys. If we had done something like the 9/11 attacks, there would have been a bunch of follow-ons already in place, timed and targeted to create maximum disruption, and part of an overall strategy. And, like Americans, we would have been embarrassed to make big threats and not deliver on them.
We've forgotten the long and well-established Arab tradition of impotent blowhardism. Maybe that's all they're about.
Oops. Too bad guys. The six-pack of whupass is already out of the fridge.