And that's exactly what the gp is talking about.
I actually used to think the same way, until I mentioned how silly some of these security theatre steps seem within earshot of someone who did some kind of Federal security work.
He went through a long winded explain of all the steps that it would to make a switch to circumvent one restriction, how much time it would take, and how it would only take one suspicious interaction by one of the group members for something to be reported.
Basically, while you can't protect against everything, by making attacks an order of magnitude harder (going from blades to bombs), you greatly increase their chances of being discovered.
You wrote that as fact, but is it? Those "highly trained" guys could barely fly a small plane, but where able to fly huge airlines at top speed.
Most terror attack in western countries where commited by lone wolves or tiny groups. 9/11 was incredibly well-thougth in comparison.