A pod-mounted Gatling is available, but isn’t flying yet (deployed) and has only another few seconds of ammo. A pod slows the aircraft and removes much of the stealth needed against ground-to-air missiles and other high-end aircraft.
Too many low-level attack planes in Vietnam (also ran by Pentagon “analysis” by McNamara’s “team” of experts ) were lost to “dumb” ground fire. The USAF generals don’t promote ground attack pilots, and so don’t have ground attack pilots in the Pentagon to argument the gee-whiz experts playing computer games against computer opponents..
All my life I always thought the only reason the Marines wanted aircraft was to protect their troops on the ground. Their version of the F-35 doesn't even have a gun.
I have worked on programs where a gun pod was attached to an aircraft and because of the vibration the accuracy was crummy.
Every A-10 pilot know loves their airplane.
The F-4 didn’t have a gun when first introduced. It was going to be a missile war, you know. After high losses in Vietnam, a gun pod was added as was training in dog-fighting. Thus Top Gun.