In individual combat it might not make a noticeable difference, but focus on my latter point to see the big picture.
The mission is done and all your surviving planes are now out of danger and ready to land. Any action after that will result in fewer points gained vs having all your planes land and tower out at that moment. The risk in points lost is far greater then the overall gain by launching a second sortie find more action.
Again. What is the difference?
Old system:
Second sortie time, I go out in my plane. I manage to kill 2 enemy aircraft, and I return to land. My side gets 2 points. Net gain, 2 points for my side.
New system:
Second sortie time, I go out in my plane. I manage to kill 2 enemy aircraft, and I return to land. Their side loses 2 points. Net gain, 2 points for my side.
Old system:
Second sortie time, I go out in my plane. I screw up and get killed. They get 1 point for the kill. Net loss, 1 point for my side.
New system:
Second sortie time, I go out in my plane. I screw up and get killed. My side loses 1 point because I didn't RTB. Net loss, 1 point for my side.
Where is the difference? If I don't go out and kill under the old system, I don't gain points. If I don't go out and kill under the new system, they don't lose the same number of points.
It works out the same.
Wiley.