Minimize pilot casualties with armor plating
Focke-Wulfs were superior to most early Allied fighters, enabling them to rack up kill tallies far in excess of their own losses. German planes relied on modifying existing designs to improve their chances against new Allied fighters as the war progressed. Late in the war, JG301 and JG4 were a threat to Allied planes, but casualties were unsustainable. The new Fw190A-9 fighters incorporated more armor to protect pilots from attacks from above and behind.