Why is the Bf 109E model still missing the head armor piece in the cocpit..?
Hopefully it isn't final.. there are plenty of pictures of Bf 109Es that were taken during the Battle, both with and without the back armored headrest.
Those with the headrest also show the curved top armor place (protecting the pilot from deflection attacks from above) present or missing.
One example being Bartlel's Bf 109E-1, WNr. 6296, forced down in air combat on 24 July 1940 - this one has both the armored headpiece, and curved armor piece on the top.
Obviously there was some irregularity with the fitting of these items, maybe preference of pilot, or unit commander, or delivery of these kits to units..
I am not sure if the engine allows such, but if it allows different 3D models to be loaded individually for each aircraft, it would be best if both options would be present for player choice, ie. player selects wheter he wants armor headrest present or not. Or it is set fixed for some units, based on photographic evidence. For example if player plays with III/JG 26, he has no choice and the headrest will be present.. if plays as pilot of other fighter unit, there will be no headrest. But probably simple player choice is better, simpler solution...