The downside to throwing civ pilots directly into heavy airframes is you wind up with the ultimate in “stovepiped” officers. These guys would know nothing about how the rest of their peers operate and have aa weak grasp of the big picture. In a big WW2 type conflict where you just need bodies and most guys will never progress beyond aircraft commander, this doesn’t matter. In a small “peacetime” military continually called on to operate in brush wars it becomes very limiting to have officers who struggle to do anything outside of their primary AFSC.

As has been said, the USAF’s primary struggle is retention not pilot production. Part of the solution will be compressing the timeline for going from operational pilot to staff geek so the service gets the needed pound of flesh prior to a pilot punching out to the airlines.