I always assumed that the rationale for the gate checks was to catch cell members who had infiltrated the sterile zone. In other words, any weapons caught then would have been a presumption of an inside job.

If gate screening was intended as a second filter to catch the items missed the first time at security, I'd say it was unnecessary.

Terrorist profiling plus *truly* random checks at security works fine for me. I'm willing to assume that everyone at the gate area is legit.