Pilots are the hard problem. It's really hard to train them, and to incentivize people to manage them. The Marines can piggy-back on the Navy's aviation personnel infrastructure.
And again, the Marines are capped on scope creep by their placement in the Navy. The Army isn't, so if they got planes that would be much scarier for the Air Force than the Marines.
And again, the Marines are capped on scope creep by their placement in the Navy. The Army isn't, so if they got planes that would be much scarier for the Air Force than the Marines.