Danny, the profiling you talk about is being done already on certain flights ouy of certain airports. It certainly has it's merits and is more effective than as you say, an induction loop + x-ray.
The problem is cost and time. It wil take at least 3 times as long to board flight. Handing over your bag and walking through the loop may takes 20 seconds max per pax. Profiling a person you take 20 seconds just to introduce yourself and the procedure, 20 seconds up to 1 minute to gather and look through documents. Another 30 seconds to ask questions. Add it all up. And this is with a normal blond blue eyed European person. Put an Arab through the system and you spend at least 5 minutes per passenger. That is the reality of profiling. You simply cannot profile a person in 20 seconds.
Cutting corners here and there (COMPROMISE!!) you might speed things up a bit. Either way, traffic will slow, lines will triple. Airlines will hate it. As I said, this procedure is in place already throughout Europe on selected flights. It works way better, but it costs and it is slow. Very slow.