The only reason I can see for not making him black is simply because you'd have to write his whole extended family and upbringing over again, taking in civil rights history into account and possibly changing timelines, or locations. Other than that, it would just be tokenism at this stage. There is nothing to gain through altering a massively established character like superman, unless you're going for an alternate universe spin on things. Changing the dynamic of a less massive hero group, like the fantastic four(who are a bit rubbish anyway, and are not as tied to a backstory as bigger solo stars) adds a new element to the relationships between the characters, making it more human.
Mixing race up in a group scenario works because it adds a new element, changing a big solo character from white to black is too much like doing it for the sake of it, and you could write up something new, or just make something about one of the black heroes.
Mixing race up in a group scenario works because it adds a new element, changing a big solo character from white to black is too much like doing it for the sake of it, and you could write up something new, or just make something about one of the black heroes.
