Here is my take on OBL and Al-Qaeda.
The various scumbag Arab dicatorships running the Middle East have made the United States (along with Israel, of course) the scapegoat for all their problems for the last 50 years or so. And while there is no doubt that dumb US policies over the decades have created some of it, the bulk of it is politically convenient propaganda drivel with little basis in reality, repeated so often for so long that it has become accepted truth over there.
Osama didn't create the anti-American sentiment in the Middle East we have seen. He has exploited it skillfully for his own ends, but it has been a long time coming. If somebody else had blown up the world trade center, folks in the Middle East would still have thrown block parties like they did on 9/11.
Bin Laden isn't a genius. 9/11 was clever up to a point, but alot about it was also stupid and sloppy, e.g. retarded Arabs skipping pilot classes on the days they taught landing. Mostly he's a religious fanatic, a cult leader with more cash and guns than usual who is good at manipulating the bitter losers of the world.
I think it is a mistake to look at Bin Laden as the leader of a group that is just using terrorism as a strategy to accomplish a particular set of practical goals. Consider this: if their goal is to get infidels (i.e., us) out of the Middle East, 9/11 caused the exact OPPOSITE to happen. Furthermore, until 9/11, U.S. involvement in the Middle East was actually at a low ebb; we just weren't that interested in it, and with stable oil prices and not much else going on, we were getting less interested and involved in it every day. If Al-Qaeda had ANY practical goal to do ANYTHING in the Middle East, 9/11 was on the face of it the dumbest thing to do. Which raises the question, if a nutjob Islamic offshoot group doesn't want infidels out of the Middle East, what could they possibly want?
The answer is, 9/11 wasn't meant to accomplish anything practical. It was meant as a gesture, a way for psychological misfits to act out a fantasy in their head about how God loved them and hated everyone that wasn't in their little club of a-holes. It wasn't meant to impress the US to do or not do anything, it was meant to show off to the home audience of mental midgets in the Middle East.
Ultimately I think we've over-estimated them in the wake of 9/11 (me included). They are mean and clever, but ultimately delusional losers fighting a loser's game. That doesn't mean they aren't dangerous, or that we don't need to wipe them out, just that we've tended to blow them out of proportion.