My understanding is that airplane facing is important for a number of things such as returnng fire from the bround in the advanced rules but dog fighting in the air between planes has no facing.
Actually it was the optional rulesetcalled the “Expanded Rules” that uses aircraft facing, and that ruleset was not widely accepted by the masses, and at the very least is not used in the official WotC tournement rules.
But yes, they made it more difficult to aircraft from the ground unless it was facing you.