Uh, you do realize that the Marine Corps already has an air wing? As a matter of fact we have FOUR different Wings: three active duty and one reserve.
And surprising enough, those wings have the ability to repair and arm and re-arm them aero-plane, fly-ee thingy ma-gigs. Heck, we even got us some cement runways.
That the A-10 cannot do.
Oh, and you know the Marines would have to acquire new weapons, weapons they don’t have, and spare parts and bigger ramp space, new avionics to maintain, tires, tools, all sorts of stuff that would hit the Marines HARD in the wallet.
So, “those wings have the ability to repair and arm and re-arm them aero-plane, fly-ee thingy ma-gigs” for the existing airframes, but not for a new airframe like the A-10.