But the question is: who do you hear it from?
You hear it not from the people complaining about the game, but from people defending the game (sort of) attacking a straw man. The complaint about RE5 wasn't that "it involves black people being violent"; it was that it involved images that are reminiscent of images from the history of racism.
It's the same with Valve and Left 4 Dead 2, the fact of the matter is that it's set in the deep south, where there just happens to be a large black population and in a zombie apocalypse, all parts of society would be affected, not just white, middle-class Americans.
Same issue: the article/blog post that sparked that off did not say that. It referred to the racial dimension of the Hurricane Katrina catastrophe: again, someone made a complaint, and people created a simplistic straw man out of it.