Current waypoints work fine and most mission builders are aware of the quirks of them. All we need is some fine tuning of the Ground Attack method in the AI routines.
A wider variety of waypoints would give a mission builder more direct control over the mission. Say you have a plane that can function as both a level bomber and a dive bomber, like the Ju-88. With the codes below, there is no way to make them dive, since, when they are above 1500 meters, they will just level bomb. If you had a specific "dive" waypoint, you could make sure they dive on the target.
These wouldn't necessarily have to be waypoints. An "attack method" (or something like that) dropdown menu could be added to the waypoint screen in the FMB.
What about the ability to set different target types? That can't be covered in any AI routine because it is mission specific. Say you wanted to have a flight of bomb loaded P-47's attacking ships in a crowded harbor. It will probably be swarming with ships, trucks, flak, and other ground targets, so the AI planes will attack everything in sight. The only way to make them attack ships only is to (a.) fly as the flight lead and order them to attack ships, or (b.) set an individual ship as the target for the whole flight, in which case they will only attack that one ship, and when it's destroyed, simply fly home. The problem could be solved If there was another dropdown menu in the waypoint section of the FMB, which would allow you to set ships in general as the flight's target. That way, they would ignore all other ground units and attack multiple ships.