Since when is the relative ease or difficulty of shooting something down a deciding factor in whether or not to put it in the game? Goons are easy to shoot down but there's still a place for them. Lots of planes are easy to shoot down but they're still in there. It's the variety of planes with different capabilities that makes it interesting...otherwise why have more than one type of plane at all?
I've always thought some type of gv-hauling aircraft would be a nice addition. It's historically realistic to add one, and more importantly it adds a tactical element that is currently lacking on some maps. Ndisles for example is an all-island map in which you can't attack most of the fields except by air. It would add something to gameplay to have the possibility of gv's landing on the island somewhere and rolling toward a field.
That being said, it would be difficult to add to the game because you have to transition the pilot from the cockpit of the plane to the driver's seat of the gv somehow after the plane lands. You'd have to figure out how to count the sortie (make it two sorties, one bomber and one gv?), you'd need some reason to land a jeep-sized vehicle somewhere which might mean adding light artillery, etc, etc. In other words I think this is a can of worms which has merit in theory but for practical purposes probably isn't going to happen any time soon.