Well, there was definitely a lot of argument around Toronto Pride with police people's uniform's being a "Part of their identity", so maybe ask those people. I don't think a uniform like a hard hat is part of an identity, and don't see it as a problem. Others obviously disagree.

The difference here, though, is respect. Cowboys, to take your have respect in north american culture. When you dress up as one, you're identifying with that part of your culture and you're saying "this is a strong, brave person that I want to emulate."

Generally, (and of course we can only ever talk in generalities about this stuff because specificity means going down into a weird case by case basis of every costume ever worn), there is a societal history in america as seeing asian people, and asian men in particular as weak and effeminate ( For more information on this, have a listen to this episode of the One From the Vault podcast which talks about crossdressing laws and how they were used to deal with asian immigration in the US). They do not have a history in the US of respect and masculinity (even the respect for Samurai is a recent thing), and usually when one makes a costume out of them, it's to get a laugh. That's the difference.

Here's the line I see: a non-Japanese person wearing a kimono to a costume party isn't worth criticism. But someone wearing a kimono to a costume party and playing up Asian stereotypes and using their fingers to make their eyes look slanty is worthy of criticism.

I think the broader point is that we don't get to decide what other people in other cultures find offensive. You can argue all day about having the "right to offend", but if you piss people off, Don't be mad if they treat you like shit or call you out for doing something they don't like, right?