Just a thought WAV; let's suppose for a moment the world was as you would like it to be, and everyone only played the music from their own nation and culture; lets also suppose that you are in a position of authority in this world. What would you do if someone transgressed, and played music from somewhere else, perhaps on an instrument not on your list of approved ones? What would be the sanction or deterrent you would apply? I'm genuinely interested in how you would propose to ensure the survival of your monocultural idea in the face of human nature and free will.
This is a genuine question; I'd like to understand how you see the mechanics of your world view in operation.