There's a lot of other aspects of the game that aren't bugs (IE, the oft-mentioned Lancstuka) that you can call a feature and anyone can take advantage of, but it doesn't make them any less gamey. Why should audio be any different?
Lock all audio into one master control. You can adjust the master, but everything else is automatically set off that and can't be individually turned off or on.
Either that, or if you dial down your own engine noise it should affect ALL engines, including those of other planes around you to eliminate any such advantage.