Well you've still got the bomb-on-plane problem, which is what the latest three rounds of security increases have been in response to -- there was the shoe bomber, and then the liquid-mixture plot, and then the underpants bomber.
You'll note that none of these plots worked. Why? Because they were increasingly shitty bombs. Why were they increasingly shitty bombs? Because they've been progressively closing loopholes. The underpants bomber might have been successful if he were shoe bomber number two, but he wasn't, because the bomb-in-shoe loophole has been closed.
People like to use the words "security theater" a lot because it makes them feel clever, and yes, the TSA like any government department has its own particular forms of insanity. But there's actual security accomplished there too. In the 1980s it was possible to sneak a 747-destroying bomb into a plane in a suitcase... now they're reduced to sticking dynamite up their butts.
Also, communications shutoff between the cockpit and outside is crazy. What happens when there's a medical emergency onboard? Let 'em die because the pilots aren't allowed to know about anything that happens in the passenger cabin?