I would think this is the most likely reason especially given the obese nature of the current crop of F1 cars.
I am not sure, since most of the cars need to have a ballast to meet the minimum weight anyway. I would have thought that inboard pneumatic jacks would simplify pit stops; the reason they were adopted in other series. Also you need one less crew in the piy lane.
Don't pneumatic jacks(the current ones) need a person to hook up the line(compressed air) to the car to activate the pneumatic jacks? That what I see them do at WEC after they pour the fuel in.
