F8F was a fleet defense fighter and was never really designed for CAS missions. The F4U on the other hand was a proven CAS workhorse. In the beginning of the Korean War the vast majority of the effort expended by carrier based naval aviation was in CAS, so the F4U and the AD pretty much carried the ball. As more resources became available, F2Hs and F9Fs for example, either through redeloyment of available squadrons or activation of reserves, even those types got involved with CAS in addition to more traditional fighter roles. It would be fair to say the the fighter role was pretty much a sideline for carrier-based fighters in Korea. Not to say there wasn't any air to air, there most certainly was and the VF squadrons were more than willing to mix it up if the opportunity arose. I believe there were even a couple of instances of F4Us knocking down MiG jets. Anyway, the bottom line was two factors, first, that as a fighter, the F8F was already on its way out the door as the carrier-based fighter business was being taken over by jets and, second, F4Us and ADs prop jobs could perform the CAS mission better than the F8F ever possibly could.
Rich
Added later . . . too bad, I really like the F8F.