Wolfgang.. the reason is also clearly stated in one of my earlier posts above. Correct me if I'm wrong, but Aces High is supposed to provide us with reasonably realistic simulations of flight models for WW2 planes, yes? Well, those planes were designed to fly from airfields most of which were under 1000ft above sea level (ASL), never mind 6000 or more!
The atmosphere a couple of miles/three kilometres up is greatly different to that nearer sea-level. Colder, less dense, lower pressure - all of which affects both the amount of power which can be generated by a piston engine and the amount of lift generated by a wing up there as against down here.
Now, OK, so the MA isn't ever likely to be anything other than walloping each other with simulated WW2 weaponary (rather than a good simulation of WW2 combat - for that you need good organised scenario games), BUT - think about game balance. Fighters have higher performance than bombers in the first place, and so can more easily take off from high altitude than bombers can. The MA has classically been fighter-bomber heaven and a pretty pointless place to fly bombers bar once in a blue moon for a number of reasons - the more fields at ridiculously high elevation that a terrain has, the greater the advantage given to fighters. The bombers - if they can take off at all - cant climb much higher, and the fighters dont have to claw their way up to them if they do manage to survive to get up to 25 or 30,000ft.
In a nutshell, putting in very high altitude fields just exacerbates fighter dweebery, and makes anything else even more pointless.
Isn't it about time we got away from that at least a little? If terrains can be designed so as to encourage more GV action and more bomber action, thus giving us all more variety, isn't that a good thing?
Esme
PS: "6K isnt even that high" - in relation to what? What's the altitude of the highest airfield you can find in the real world? (It's in S America, IIRC) What are the retrictions placed on aircraft visiting that field, and why? 6K isn't all that high to FLY (although 1930's airliners often flew at about half that altitude - no cabin pressurisation), but it's damned high to TAKE OFF from!