I'm not really expressing an opinion either way here...but here is another perspective.
Much of the data you see on G-tolerance is pretty modern. In WWII very few pilots were career pilots (or even pilots prior to entering), most were "converted" civilians. For many, when they hit the "big show" they weren't what you would call experienced fighter pilots. Most veterns I have spoken with relate having a shockingly small number of hours of flight time and only a small percentage of that in the high-performance aircraft they would eventually fight in.
They also didn't have a temendous amount of A2A experience to build up their G-tolerance skills. How much experience did the most active fighter pilots actually see by the end of the war?
What was their physical state at the time? Most G-tolerance studies use fresh, well rested subjects. Most WWII pilots flew very often, and on very long missions (think about ETO escort missions), where the opportunity to die quickly was present on every flight. Many vets I've spoken to tell me they felt tired, emotionally numb, and mentally fatigued a lot of the time. Then take a more extreme example of a pilot on Guadalcanal in the months following the invasion...exhausted and suffering from the effects of Malaria and Dysentery (dehydrated, fever, chills, etc.)...many pilots were carried from their a/c on landing. Not exactly a well rested subject

To me, the question is what do we want to model, the "typical human" or artifically adjust the "typical human" to make the "typical WWII pilot"? I can see arguments both ways.
-Ogre