Why is it a cultural inappropriate?

because SJW-trolls need an excuse to make actual activists feel bad about themselves.

Real cultural appropriation is when you claim an ethnicity you don't even speak the language of, or claim that coleslaw and apple-pie are american inventions

Just about all cultures are pleased when other people learn their language, try their food, wear their clothes, copy their hairstyles, etc etc. It is not cultural appropriation to do so. 

I think most people are just fed up with non-sense surrounding the concept.

This stuff has always confused me since my mother was born in Latina (still located in Europe). Yet, Latin Americans often seem alien to me.

I've been called a racist for just for doing something culturally Roman because some idiot felt I was making fun of American Native tradition ... but then I'm used to being called a racist. It happens to every blond haired male living in the US.

They are....when they sell you the outfit at a 75 percent mark up.  

I would say it is not culturally inappropriate, because, for example, in schools, there is usually International Day or creative ways to appreciate other countries by learning about their dance or their drama. Many countries have done the hula, tango, etc. The only nationality I know of who are sensitive to wearing their costume are the native Americans because it has significant meaning to them, which is understandable. Respect is necessary. As long as you carry the clothing with respect, I think many would be pleased to see their traditional clothes worn by foreigners.

Only white people can be guilty of any sins.