Well, in the scenario where the hijackers are unarmed, it doesn't help that much, if at all, so that doesn't support my case, I guess.

However, let me ask you this: we've all seen the reports about how investigative journalists today have managed to sneak weapons, guns and knives onto planes past the TSA security personnel, with degrees of success varying from airport to airport. If we eliminate security checks altogether, how does that improve security at airports with low degrees of success at catching loaded guns/knives/weapons/contraband?