A new feature that would be extremely useful is the ability to rappel from things. The KA-60 (Black) seems to already have the supports for the rope to be attached to.
This would allow pilots to stay in the air and hover over the drop zone. In addition helicopters could come preloaded with the rope in their inventories that is deployable/retractable by either the pilot or one of the passengers sitting near the door. This would also mean that a door open/close animation would need to be added.
Players could also load rappel ropes into their backpacks for use of rappelling down cliffs or buildings. (This applies more to Altis than Stratis.)