In your sarcasm, you got it right. The point of things like TSA is not to actually keep America safer, but to give a perception of safety to the citizens. That way, if anything bad happens, the folks in charge can shrug their shoulders and say "well, but we did everything we could..."
I'll give you a for instance: as recently as 10 years ago (and probably long before that), everyone knew that you could use liquid explosives to blow up an airplane. In fact, the US foiled a terrorist plot to blow up an airplane using explosives disguised as ordinary liquids. But there wasn't a need to ban liquids from airplanes because they weren't perceived as dangerous.
Fast forward to last year when the British arrest some folks with liquid bombs, and *suddenly,* liquids are no longer safe to carry on airplanes? Huh?
The level of risk hadn't changed--we all knew this was a possibility--but the perception had changed. This was all over the news, so the government had to do something to make it look like it was doing something, so it banned liquids. Completely asinine, but yet designed solely to ensure that there was an acceptable perceived level of safety.
Same thing with the TSA itself. There was a reason why the government contracted security out before 9/11--it was cheaper and more efficient. But after 9/11, the government has to make it look like it's doing something, so it takes over security and announces "See? We're cracking down on terrorism. Everything is fine. Nothing to see here. Carry on."
If that's the case they shouldn't let any powders on the planes either. I can think of a few that will take an airliner down.