The security gate really is useless. If terrorists wanted to do any damage at all they'd simply walk to the security line and detonate their bomb. You could probably kill just as many innocent people on a busy day as bringing down a jet liner.
Brute force security will never work. Israel got this right years ago. As an example, (I'm not an American) I travelled to Amsterdam, (Schiphol airport, one of the most secure airports in the world). Even before checking my bag in I was confronted by airport security and asked for my password etc. He never asked to touch my junk, he simply ask me some straightforward questions. Like, why are you here, where are you going etc. Based on my responses he was able to make an intelligent decision that I didn't need further screening (no doubt I had remote eyes on me too). The gist of it is that less intrusive, more elite force security will get you MUCH greater results. TSA != intelligence and intelligence is exactly what we need but we're too damn cheap.
Every single country that has dealt with terrorism knows that brute force is exactly how the enemy wants you to waste your resources.
Terror has won when we are kept captive by ourselves.