I don't see this feature being added to the game until more air units are added but essentially the addition would allow for the larger helicopters to move ground vehicles around the battlefield. This would allow for vehicle to be extracted for repairs and returned to the field quickly.
Another aspect would be para-dropping vehicles from cargo planes like the C130. This was a feature I was sad not to see in ArmA 2 as it would allow for units to be dropped in with vehicles. Another point onto this would be to allow ammo boxes loaded and dropped with a parachute.