Don't forget this game doesn't simulate hits on the controls. These planes are packed to brim with control equipment (wires, levers, electrical, hydraulic, etc.). One bullet in the fuselage can do a lot of damage. The possibilities are limitless.
HTC may have taken that into consideration when they modeled damage to the individual control pieces. Only HTC knows for sure. I'd like to see variations of damage, instead of "all or none", I wish there was a way to "reduce" the damages done to aircraft and gv's in AH. The all or none is a bit drastic of a damage model.
All one has to do is look at the pictures of damaged aircraft from WWII. There are lots of photos of aircraft missing half a rudder, or half an elevator, etc. I've been told personally about bombers taking damage no where near a turret that had been knocked out, meaning the hydro or electrical system had been knocked out or damaged.
Evidently there is a sneak peak of sorts in the WWI arena and the WWI aircraft with regards to how the future damage model in the WWII arenas are going to be.