(That's partially because the A-10 was designed to do one task well and the F-35 was designed to do everything somewhat poorly.)
AF jocks plain don't want to do CAS at all, they want to launch missiles from 200 miles away and 20000ft up. But they want the army to have fixed wings and do its own CAS even less.
They hate the A10 because the A10 was created solely to do CAS. It flies low and slow, its only job is to support grunt, and it does that extremely well. None of that gives AF jocks a stiffy.
The F35A is also supposed to be able to do CAS missions, especially with drones that can deliver fuel to the uncontested battlefield.
AC130J is losing the gatlings and the armor.
> The F35A is also supposed to be able to do CAS missions
Operative word: supposed.
And nobody will send that expensive an airframe at the ranges and a10 operates at.
Then why is there a Gatling gun on the F35A?
Using one multi-purpose aircraft has some fantastic advantages if you can pull it off.
A carrier can use all its combat aircraft to fight enemy aircraft (effectively double the number of anti-air aircraft on board), then after the enemy Air Force is the destroyed, switch around to using all the F-18's to attack ground targets.
With specialized aircraft types, some combat losses focused in a particular role can cripple the entire air wing, whereas with multi-role aircraft, you can keep right on operating.
It's great from a maintenance, logistics, and training as well.
The Air Force doesn't, but the Navy does.
The thing that everybody leaves out about the F35 is that you can take a relatively small ship, put a half-dozen F35's on it with some drones, and you have a tiny carrier with a remarkable amount of firepower.
So, now you don't have to sail your gigantic ass Nimitz carrier into the forward theater where a lucky cruise missile hit can cripple your entire fleet capability.