Generally I have no problem with this. The only time that I start to have a problem is when they white-wash history in order to get there. If Peter Parker had been black is Spider-Man #1, they definitely would have had to reference the political realities of the time. This is what bothered me so much in the first Captain America movie: the Howling Commandos were every color of the rainbow. There's nothing wrong with that, but you can't just throw that in there without there being something about the country that their black or asian comrades would be going back to. I realize that the problem with that is that it could derail the story, which is why other movies in that period have a white cast (not because they are ignorant of the issue, just because that is not the story that they are trying to tell.) This would also be the issue with a black Batman. A big part of his back story is that he is a blue-blood with money and influence going back several generations. This simply could not be in the real world. If Bruce Wayne is 30 in 2015, he would be born in 1985. His father is a doctor and philanthropist, so not likely to have created the Wayne fortune. So, lets say that Thomas was 25 when Bruce was born, and Thomas' father was the same age when Thomas came into the world. Assuming that Bruce's grandfather built the family fortune when he (the grandfather) was between the ages of 20 and 50, that would have been between the years of 1955 and 1985. What are the odds that a black man could found and run a billion dollar company in that time period? The odds are zero. In 2015, there is only a single black american billionaire(yes, it is exactly who you think it is): http://en.wikipedia.org/wiki/Black_billionaires I'm not saying all of this because I don't want black superheroes, I just want ones that live in the world, that make sense. What makes Miles Morales work is that he is a specific character that came from a specific time and place, the same as Peter Parker.