I completely agree.
I'm not even American, which might be part of the reason I apparently don't 'get it' (even though I'd consider myself pretty aware of America's history and culture), and I've not read the entire thread, but from my perspective the whole thing just seems like people making a big fuss over nothing (in this specific case of course, I'm not saying racism is a non-issue. Just repeating that to be sure people don't understand me the wrong way).
If you are truly offended by this, I'd love to hear a reason why other than " 'cause racism" or "because of [insert explanation of historical context which has nothing to do with this here]". I'm just wondering how someone cosplaying someone else with a different skin-color clearly without racist intentions is something that offends you in a significant way and not just because society implies you should be offended. I'm not trying to be insensitive, just curious because it seems really weird to me.
I'm sorry, but this argument is bullshit. You're saying that because you don't feel the need to do it, it is wrong for others to do it? I'm not implying it is
necessary to paint your face another skin-tone if you want to dress up as a certain character, but really, why should it be such a problem if someone wants to do so? It is, after all, more accurate. If you for example want to be Billy Mays for Halloween, I wouldn't have a problem with you putting on some white facepaint to potray him better nor would most of the 'white' population. Situations like in the OP being called racist is all because of the 'historical context' which has nothing to do with it at all (when we're talking about costumes that aren't racist on purpose, like 99% of cosplay isn't (including the one in the OP)).
Your argument at its core depends on the assumption 'white' people would be offended if 'black' people did the same, which I can almost 100% sure say isn't true (if so, where are the outrages about those situations?

).