Although I do not agree with what appears to be your assessment of what cultural appropriation is - it is more complex than merely borrowing from other cultures - I do think you make an excellent point about how cultural cross pollination makes art better. If, for instance, White people were not allowed to sing soulfully because soulful singing is for Blacks only, we wouldn't have blue-eyed soul. And I wouldn't want to live in a world without blue-eyed soul.