One benefit to having real craters on the ground is that it works to the benefit of the furballers like Lasz -- because virtually all the fighters of the period could take off from fields that were only marginally improved (i.e, grass, graded dirt, etc.), it's going to take a lot of bombs to cover a field widely enough to prevent fighters from coming up at the field; they may have to do some work taxiing around the craters to get to where they have enough clear ground to launch, but the big bombers need long, flat runways and don't steer as well; they're much more vulnerable to field-cratering.
And I don't know that it would even require making the graphical crater collidable; the FE should know where each of the wheels are -- it has to know that to handle landing and takeoff -- so you could fake the effect of going into a crater by using the crater position and diameter to adjust the ground level under each wheel to make the plane/vehicle tilt as if a wheel was dropping into a crater.
One thing I would like to see, and which should only take a small amount of programming, is to enhance the graphics by defining ground objects as either vertical or conformal. Vertical objects, like trees, are placed vertically regardless of the slope; conformal objects, like craters and the stupid white rocks, are placed to lie in the same plane as the ground. This would eliminate the wierd effect of having craters sticking out from the hillside like wood-ear mushrooms -- a crater in a 45° slope should be in the slope, not sticking out from it like a shelf.
