As for white - I like sigma's idea in the sense that we are talking about whether you are discriminated against in your society because of your ethnicity. Now in my society I am not. I have however experienced the really weird feeling of being a minority while in certain countries. The reason the feeling was really weird was because there was a wide spread feeling that my ethnicity actually made me better. It resulted in obvious unsubtle systemic favouritism. Stuff like not having to wait in line, being literally pushed to the front of lines, waived through police checkpoints, when literally every other person was being frisked. There was some downers but most of it was positive. The funny thing was even with most of it being nice it was really uncomfortable. I can't imagine how awful that would be systemically in reverse.
As for the appropriation thing. First I agree that if you think you are an expert on all things japanese because you eat at Sushi train and say 'Moshi moshi' when you answer the phone makes you a wanker. But its not cultural appropriation and it's not an erasure of a particular culture. Nor is getting kitted up in a kimono, wearing dreads, saris or bindis. There are other things which involve the fetishing or misappropriation of matters which are of cultural significance or taboo. But mostly trying to learn another language, trying new foods and exploring a foreign culture are good things. Most people who are in that culture appreciate it. The problem really seems to me that you have Americans, with a particular ethnic identification, who feel that you are stealing their thing, oftentimes when they have never been to that country themselves. Now I understand why these Americans are a bit pissy about this. They were probably marginalized or made to feel like shit for being of whatever ethnic extraction and now to have all the arseholes you were at school with jump on your bandwagon as soon as it's cool and diluting your cred would suck. But it's not a real social justice issue, so much as a proliferation of wankers.