It is true that it is hard to justify perking the C-Hog on the basis of its performance as a fighter alone. But it is the only 4-cannon bird that is CV capable. Also, it was a historically very, very rare version of the F4U that would be the majority of Hog sorties in the MA if unperked.
BTW, don't compare quad Hispanos to German rides. The MG 151 is considerably less lethal than the Hispano, 109s only mount one of them, 190 A5s have only two of them plus a very small amount of ammo for the inneffective MG/FFs, D9s only have two cannon. The A8 can carry quad 20MMs plus two machine guns, but guess what, that package *still* is not quite as lethal as four Hispanos. 30MMs are utterly lethal of course and also an utter nightmare for most of the player set to aim.