You know there are more emotions related to "shit you don't in particular like" than offended, right?
People care about different things, and for people who are say, above average interested in world history, race bending just for the sake of it might be perceived as anything from insulting to their intelligence to just silly and ultimately just uninteresting.
Offended has become this nonsensical catch all phrase that gets thrown into every situation where someone expresses some form of dislike, and it's well, silly.