I've once thought of increasing overall realism, but soon realized that it definately wasn't a majority opinion. I'm not sure just what exactly you are picturing, but I can take a bold guess that what you want would probably be fulfilled if Combat Tour does arrive.. (although it is more and more smelling like vaporware).
Nowadays, I mostly wish for very small, detailed, situational depictions which can greatly increase visual realism and immersion without disrupting any of the gamplay or requiring better PC systems.
For instance, the gear. Most WW2 planes rarely had such perfectly synchronized hydraulic landing gears. Thus, when they take off you will usually observe one landing gear folding in before the other. Now, how difficult would that be in implementing? I'm guessing HTC could probably do it in 10 minutes. However, such useless and trivial detail it might be, and yet that alone increases the immersion rate of the game.
How about screen shaking? I've also suggested this for years. In the old AH1, we didn't have the screen-shakes when firing a gun. This simple effect was added some time before.. why just use it with guns? How about flak? A 88mm flak bursts close to you.. boom!... the plane shakes.. the second burst was even closer one.. BOOOOMM!!!... a bigger shake on the screen... incredibly minor detail and yet, this is bound to excite dedicated buff fans. Or, how about when it is used on ground explosions? You are in a tank, and somewhere nearby, an enemy aircraft drops the bombs.. BOOOOOMMMMMMM!! Wow, what a shake...!
...
I have about a hundred of these small ideas, which does not effect the gameplay whatsoever, and has minimal impact on PC system requirements, and yet, could make AH2 soooooooar in immersion. It's a pity HTC is still too busy doing God knows what, to consider these kinds of small stuff as priorities.