The weird thing about dreadlocks is who owns the rights to being lazy about their hair? Rastas claim it as a part of their religion, but wearing one’s hair that way predates their belief (plus some are liable to get offended when any non-believer, including other Jamaicans and blacks from outside the Caribbean, wear that hairstyle.) And one culture adopting part of another culture is as old as history-- I once witnessed an argument between a Greek and Turk over who had the right to claim the bouzouki as their own. That said, I agree that non-Natives wearing Native American headdresses is not OK.
I make jokes about white dreads, but I will admit that I briefly considered them when I was a teen and they weren’t common (thanks Dave Pirner of Soul Asylum).