I don't think that this is intended to be a tank/vehicle sim in the way some are thinking. Whereas something like ARMA tries to cover all bases equally, I think the idea behind this is to provide a greater sense of immersion in a flight sim than would be possible without drivable vehicles and the like. Maybe I'm wrong but thats my take on it.
I just had a thought though, imagine a campaign where you've wrecked too many spits so you get demoted to driving a staff car for the rest of the war, hmmm, I've just decided I don't want that level of immersion....