The main benefits of cultural diversity would seem to result from being able to selectively adopt the best and most interesting ideas and practices (e.g., food, fashion, music, language, etc.) from everyone and every subculture in a society and imitate and use them – out of admiration for the diversity those subcultures have to offer others.
At one point, eating a burrito in most parts of America was probably both rare and weird. Then, burritos and Mexican food got enthusiastically “appropriated” by Americans, became absolutely mainstream cuisine over time (e.g., Chipotle). To our collective benfit, a foreign culture became less strange and more accepted by Americans, to the point that salsa eventually started outselling ketchup.
Isn’t this what we want? Isn’t this what any subculture should want? If people say “Hey, that’s a very attractive style of dress or hair style! I’d like to dress like that or wear my hair like that!” they are paying you a huge compliment of admiration and imitation, not trying to steal or “appropriate” anything from you.