I understand your point and agree with it to some small degree, but think we've all gotten a bit too sensitive about what can be shared and what can't.
The only way cultures evolve is through appropriation of elements of other cultures. Where would Christmas be without the appropriation of the German Christmas tree? And if you don't think travelers picked up bits and pieces of dance, art, and costume from other cultures as they traveled the Silk Road or the Seven Seas, you're wrong. (Pasta, anyone? It isn't originally from Italy.) One of my favorite customs is the lighting of luminarios, a custom from Mexico.
To willfully misrepresent an individual culture in jest or with derision is one thing. To embrace appealing elements from another culture into one's own life is the way of the world and has been since the girl across the river decided Eve's fig leaves were a good idea.
I recall seeing a video of square dancing done by a group of aficionados in Japan. Their version was very funny to my western eyes, but at the same time I was so pleased that people a world away loved this dance style so much than they were making it their own, right down to the dozen petticoats and white cowboy boots (which no American square dancing lady would be caught dead in, but what the heck- it's their version).
Maybe viewing "cultural appropriation" as "cutural sharing" has to do with growing up in the giant cultural experiment called America.