The fact that the RNZAF during WWII was attached to the US Navy, probably had something to do with it. Of note, is that the FG-1D's were a special order by the RNZAF.
The F4U-1/FG-1D were used by great effect by RNZAF pilots in ground attack (especially using 450lb depth charges).
Having just said all that, the replacement for the war wary F4U/FG-1's was to be the NA P51D Mustang, if the war with Japan was to carry on past 1945.
Personally too, I'm glad the RNZAF received the Corsair.