People about Cosplay...
Putting aside for the moment that the tone of the question doesn’t imply the most open of minds, cosplay is – simply – acting. Do you consider Mel Gibson, Ken Branagh, David Tennant, Cumberbatch, et. al. immature for wanting to dress up and act as Hamlet? Cosplay is a similar – if not identical – mindset: people, inspired by characters, possessing the right combination of talent, bravery and self-awareness, performing as said character for an audience. Whether it’s a convention stage or a Broadway stage makes no difference. The person who portrays Deadpool or Master Chief is very much spiritual kin to the person who plays King Lear or Hamlet. It’s wrong to praise one and denigrate the other based on the source of their inspiration, for to declare which works are “great” and which are not is subjective or worse. Still, even if most consider it blasphemy to compare Marvel to Shakespeare, the motivation to portray characters from either realm is identical and the healthy mindset WON’T criticize this, realizing that whatever it doesn’t “get” is not automatically inferior or invalid.
PS: Ironically you will find, if you but ask, that most cosplayers as children were very successful Trick or Treaters, as Halloween is quite often the “bug” that bites them for their subsequent motivation.
To answer your main questions, No and No. Cosplay is supposed to be about inclusiveness, fun, and showing your love for a character.
That being said, as with any group of people, there will be jerks on both sides. There will be those that make their costumes and look down on those that buy them, and vice versa. Jerks can be found at all levels of cosplay, just like regular society. And just like regular society, you have the choice to ignore the jerks and go your own way.
If you are happy with your cosplay, not competing in a 100% bought cosplay and are having fun, that really is all that matters.
People who make their cosplays receive just as many nasty comments and critiques as those that buy them by the way.
Interesting question. If the word “cosplay” is referring to what is usually meant, then no, because the costumes in question are those of fictitious characters. There is no “culture” being appropriated. Not even if you wear a Japanese school uniform – because Ayanami Rei, or whoever, is not a Japanese girl, she’s a fictitious character and you are dressing like her.
There’s some interesting weirdnesses to explore though, even in this space. Some thoughtless racist fans were in the habit of making black cosplayers feel uncomfortable. The absurdity of this is almost galactic in proportion because if a black woman can’t dress like Sailor Moon because she’s not Japanese, then why would a white women be able to? She isn’t Japanese, either. And Sailor Moon is not Japanese, she’s fictitious. Obviously, critical thinking is not high on the list of people who are unpleasant to other people.
But the rising tide right now is that cosplay is for everyone and while I don’t myself cosplay, I support this. Dressing up as your favorite character is not cultural appropriation – it is a culture in and of itself. There are folks who cosplay Jane Austen characters and pirates and princesses. Cosplay has its own subculture aesthetic. Merely dressing up is for anyone, anytime, anywhere.
The world has adopted the word cosplay. It’s Wasei-eigo, which means the word was originally created by the Japanese using English as the roots. “Costume play” becomes “cosplay.” There is a world cosplay summit. So I don’t think you can argue that merely using the word is appropriation. Words for things spread. That’s how language works.
Calling offensive stereotype costumes “cosplay” is stretching the word uncomfortably outside what cosplay means, IMHO. Those costumes are meant to represent offensive stereotypes. It’s outside the culture of cosplay itself and is merely wearing a costume in bad taste.
So, I would say no, cosplay is not cultural appropriation, it is its own culture that is open to anyone, anywhere.