People about Cosplay...
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.
What is the appeal of acting, and even role playing for that matter? Cosplay is firstly an opportunity to completely put yourself into the character’s shoes, act out a role. Additionally it is a way to showcase your craftsmanship. Just because you view something as juvenile doesn’t make it unappealing. You should be criticizing community theatre if you have that view.
Personally I feel that cosplay gives an opportunity to also put aside your own shortcomings and be someone else for the day. I feel exceedingly confident and friendly in a costume and when I see someone else in a costume, I can “know” who they are and be recognized myself. There’s a level of comradery and confidence in it. Hope that helps.
Cosplay is used to portray a character, in complete characterization, sometimes even down to speech and acting.
Culture appropriation, in my opinion, is always negative, portraying double standards that favor white people. For example, hairstyles used by black people seem trashy and inappropriate, but in white people they are deemed edgy.
Cosplay is a representation of the love for a character, they are acting as the character, their race or cultural background of said character usually has nothing to do with the character, it is a simple fact about them.
When a person does “cosplay”, by making fun of another race, say they dress up as a black character by simply putting on brown makeup, this is racism.
However, correctly portraying the character who happens to be black, is cosplay and is not appropriating the culture of said character, simply using their image to act as them.