On the one hand, you have laptops just sitting out where anyone could grab them while their owners are waiting on the other side of the body scanner.
On the other hand, any potential thief has presumably been in full view of security cameras since at least the point where they handed their ID to the TSA to be checked and scanned into a computer which presumably logged it… Seems very risky to me. Same goes for on the plane, where you’re in a population of a few hundred people at most, all of whom are listed on the passenger manifest.
Anyway, from the movies I’ve watched, I’m far more terrified by the idea of someone planting drugs in my bag while I sleep on the plane than taking any of my stuff out of it.