I would posit that the screening checkpoints are actually worse in preventing the next hijacking than they were pre-9/11. Though it has been over five years, the WTMD and x-ray machines are not really any better. The puffers may be better, but it appears there have been some issues with them. And they are easily avoided by anyone that wants to since so few have been deployed.

But what has happened is that the list of prohibited items has so greatly expanded from toothpaste to water to pocket knives that it becomes much more difficult for the screeners to find the items that really matter (e.g. EWR's 90%+ failure rate in a test that was leaked). If I ask you to look for just three items when you are screening, you will be much more likely to find them than if I ask you to look for 100 items of which those three are a part. It is just the way our minds work. As such, the items that really matter (guns and explosives) are more likely to be missed now than they were before IMHO.

Where we are better off post-9/11 is that we now have hardened cockpit doors and a different approach to how we deal with hijackers. Flight 93 is an example of that. If those passengers were forewarned earlier, they might have been able to prevent the hijacking. As it was, they did prevent the hijackers from destroying their intended target.

So are we better? I think yes, but in spite of TSA screening points.