That's part of the reason the P-47 and P-38 were phased out of service rather quickly after WW2. It was simply cheaper to build/maintain P-51's over the more expensive P-47s and P-38s.
I came back to bite them in the butt in the Korean War. The US had to field P-51's in a ground attack role, a role it was never really designed for. I am sure may good pilots lost their lives due to a radiator shot from rifle fire. P-38s and P-47s would have survived this kind of fire more often.
Curiously the F4U was kept in service by the Navy (barely stayed alive) and it became one of the premier ground attack aircraft of the Korean War. Similar to the P-47 in a lot of respects, radial engine, could hold a lot of weapons and very durable. I am sure a lot of Navy pilots were glad the F4U wasn't phased out of service as quickly as the P-47 was.