Appropriate appropriation?

I recently read Sherman Alexie's The Absolutely True Diary of a Part Time Indian, of which Neil Gaiman has said "I have no doubt that within a year it will both be winning awards and being banned." It's a semi-autobiographical coming of age story about a kid who lives on an Indian reservation but attends an all-white school outside of it. The book pulled me into this reality that is miles away from anything I've ever known, but that I could relate to on just about every level. I recommend this book so hard.
There's this scene in the end of the book, in which a character's grandmother has just died and pretty much the whole reservation shows up to mourn her. She was so beloved and well-known that they have to hold her memorial at the high school football stadium. People stand up and tell great stories as a tribute to her memory, but it's this one white guy, the narrator says, whose story was most important of all.
His name's Ted, and while he's not an Indian, he feels Indian in his soul (just like every other white person the narrator's ever met). Ted proceeds to give this long resume of all the ways he respects Native people, all the arrowheads and art and blankets in his collection. But the most beautiful item he owned by far, he said, was a powwow dance costume. The dance costume, he tearfully confessed, he knew had been stolen, and now he'd searched for ages to find the original owner - the very woman being mourned that day. 
Only they didn't belong to the grandmother at all. Ted didn't even have the right tribe. He'd shown up and derailed this old woman's funeral, made himself the center of attention, no doubt hoping for a big tearful display of forgiveness, and he was on the wrong damn reservation. 
And that's the first time I really understood the concept of cultural appropriation. I knew the term, of course, and I knew it was supposed to be bad, but I never actually got why it was. I mean, melting pot, right? And it's not like culture's a limited resource. It's not like tourist shops are in any danger of running out of dream catcher keychains.
But old white guy Ted made me get it. He wasn't just a pretender, he was a thief. He stole a funeral. He stole a family's grief. He paid money for a thing he didn't understand or have any right to own, and then he thought his crisis of conscience entitled him to steal glory away from a dead woman. This guy had everything, and the old woman, well, she'd lived her whole life in the shitty slum that was all that was left of her people's ancestral homeland. Yet he was the one stealing from her.
But I'm bordering on whitesplaining; lots of people of color have explained the concept better than me. 

But it's not just Native American culture that gets appropriated.

I do kind of take issue with some of what she says about hair. There are ancient Greek statues rocking dreadlocks*, and lots of cultures throughout the centuries have used intricate braids. The baby curls Katy Perry (who is, admittedly, an awful human being) got flack for wearing... my Irish grandmother called those spit curls, and she used to put them in my hair just like her mom had done for her. But Amandla Stenberg has a counter-point.

In my mind, the difference between cultural appropriation and cultural exchange is respect. And I kind of think that if a person can't see the line between cultural exchange and perpetuation of offensive stereotypes, it's probably safest to just not go anywhere near the line. 
And if you're like me, and are still not really cool with anybody telling you what you can wear or do with your hair, some perspective might be useful: while we're indignant over being told what we can't wear, the American government still tells Native Americans they can't have running water - many reservations still lack the infrastructure to support it - in fact, a full 40% of Navajo Americans aren't able to get water in their damn homes. The government has also told Native Americans on reservations that they can't have adequately funded healthcare. Medical facilities on reservations are so drastically and shockingly underfunded that you get to live like, five years longer than Native Americans, on average.
Be mad about being told what you can't wear, but save your righteous indignation for stuff that matters.
      

* By the by, you know that viral video of a person of color attacking a white guy for having dreads? Please stop treating individual crazy people as representatives of their race as a whole. I once had a white lady (who happened to have schizophrenia) beat me up because I offered her a sandwich. This was not some white schizophrenic uprising aimed at oppressing people with sandwiches, it was one unstable lady being unstable.