In a short term sense, I don't disagree. However, I think it's important to consider the law of unintended consequences. For example, if you were targeting the KKK in Alabama, and you decided to pull over every middle aged white guy and searched them when they left the state, what would you really accomplish? You might catch a few people at the very first, and an occasional complete idiot after that, but that would be extent of the upside. On the down side, you would piss off every middle aged white guy in the state, and perhaps make some of the sympathizers.
Now, I'm not saying that there shouldn't be some extra scrutiny on certain people that fit a profile. On the other hand, you go very far down that path, and suddenly everybody who isn't you starts looking at you like the enemy. The West is going to need friends in the Arab world if we don't want to be dodging bombs all the time, and singling out the people who will most likely be most sympathetic to the West (ie, students, business men, techies, plus the guy at the kwiki-mart) is probably not the best way to win friends.
It's a fine line, and I don't think there are easy answers on this. The "kill em all, and let God sort it out" just ain't going to work no more.