"Will HTC ever consider the option of filling these empty voids?"
Why bother? Seriously.
When you're in combat you couldn't see the other pilot even if he was there. VERY few times did opposing parties in aircombat get to see each other in any detail. And to model moving levers, control stick and pilots arm/hand ala "some other place" is hokey, useless and a really bad FPS black hole. Not to mention "development takes time" and I personally would rather have a improvements to AH that matter like (cough) removal of auto-retract flaps, addition of metric guages or even changeable skins for the aircraft than something like a detailed "pilot" constantly viewable in the cockpit.
Which he is there when you're about 20 yards away form the plane in external view mode. Just not highly detailed. That "pilot" disappears when you get up REAL close to the plane and then you can see the working 3D virtual cockpit just as if you were in it and "flying" online.
All IMHO of course
Westy