The whole point of the term 'political correctness' is that it is a 'pejorative term used to criticize language, actions, or policies seen as being excessively calculated not to offend or disadvantage any particular group of people in society'. The whole point of introducing more than just white American men is to appeal to a larger audience and so Marvel can improve their overall image, just like how companies do diversity reports. I doubt they're doing it to reflect upon the real world, but then again I'm not Marvel.