It's a compromise (as with anything in aeronautical design). The Jerries had a completely different design philosophy that didn't allow for placing one man alone in a turret far from the rest of the crew. For psychological reasons the crew compartment was designed so that the entire crew would be fighting back-to-back like in a foxhole, where they could give each other mutual support and keep each other's morale up. It's a philosophy that was studied and to a large extent adopted by the western allies after the war. The experience of being a tail gunner in a U.S. or British bomber was defined by loneliness and mortal terror.
