There were two primary selling points when KCM was launched.

Eliminating known crewmembers from screening checkpoints:

1. Allows TSA to better focus its screening resources on everyone else, thereby “increasing security”.
2. Reduces security wait times for the general public.

You can Google old press releases about CrewPass / KCM and see those two commonly repeated themes. Speeding up crew screening was never a major selling point. Pre-KCM every airport either had a crew/employee line that put us ahead of the general public, or they would let us lift the rope at the front of the screening queue and go right to the front. I never once waited in line at any screening checkpoint in the U.S. while in uniform.