Act now, ask questions later. Best policy.
Except it didn't really work, did it? For all the blowing up of misplaced luggage, the IRA still managed to execute several high profile attacks, not to mention the constant attacks on British Soldiers. I mean sure, it looked like the government was preventing terrorist attacks, but there's no evidence that suggests they where successful. Which is why we need to be even more vigilant/paranoid than before 9/11.
Yeah, because if you can't stop a bunch of maniacs with boxcutters, you're gonna have a really good chance preventing someone who has a bomb.