The COIL laser weapon only lists missiles as possible targets. I know that it was primarily designed to kill missiles in the boost phase, but should aircraft be added as possible targets, too?

From a game perspective I don't believe it would be prudent to allow targeting of aircraft with the ABL.

 

Real Life Issues:

• The targeting system was not optimized for that use.
• It likely would have taken multiple "shots" to assure a kill of an airplane, these shots not being cheap in the first place.

Game Issues:

• In many situations, the ABL would become the air to air weapon of choice due to its range and high hit chance. While the player might use it sparingly or only in self defense, the AI would waste shots on aircraft instead of saving them for ballistic missiles.