There are half a dozen other reasons having nothing to do with flight modelling why gunnery and ACM is like that in AH. Most of them relate to the fact that as we play the game we aren't sitting in a real plane and we aren't really looping and turning through the sky at 400 mph.
That the aircraft were capable of "amazing" reverses and other maneuvers is not in much doubt. The question is whether most pilots were capable of them. The physical stress that G-forces caused a pilot made any more than a few hard turns every few minutes out of the question for the majority of flyers.
Besides that, most of these pilots were "newbs" with much less combat experience than you possess from AH. Nobody but the most cool-headed aces considered pulling such daring maneuvers. Many didn't even know how, and many others were too excited by combat to plan a complex maneuver, and without the experience of hundreds of dogfights, they didn't have an automatic instinct for ACM like many AH pilots. They were just thinking about living through the engagement and maybe even being lucky enough to get an enemy under the crosshairs.
Look at the gunnery in some of the clips in that movie. A lot of the time the tracers aren't even coming close. Forget about proper lead, they aren't even remotely on target. It's not because the plane isn't accurate, it's because the pilot is so excited to have an enemy in front of him that he's almost firing wildly. Possbly combine that with exhaustion and you don't have a likely situation for pinpoint gunnery.
We have the luxury of not enduring any forces of inertia as we play AH, as well as being able to access any controls for the aircraft we need without even having to move our hands. Combine that with the fact that we're lucky enough to be able to live and fight another day no matter what happens, and it's no wonder that you see far more marvelous flying in the sim than in reality.
AH's damage model could probably use tweaking, but there's not much wrong with the flight modelling, and AH will never perfectly represent WWII combat in the way you want.
