Eyecue,
You make an interesting point. I'd say that the real solution is to subject every single person to whatever screening is necessary to determine whether he or she has a weapon. It makes no sense to super-screen only a small percentage of people, because whether you choose them randomly or by profiling, you're still letting 95% of the people go through without doing whatever search is really necessary.
To have the super-screen lane is to admit that the regular screening lane is missing a lot of contraband. What's the point? Screen everybody, or screen nobody, but the half-assed, well, we'll screen two percent or eight percent of the people is embarrassing.
(I have an ulterior motive, obviously. I"m convinced that if they treated every woman in the disgusting manner they've treated me at a checkpoint, the TSA would be toast by morning.)