I don't think it's quite so simple as "cause some people are racist." Yes, we learn about the Tudors, etc., but in countries which are or were, to a large degree, peopled by predominantly white people, it is natural that the history would concern those events which affected those countries. When I was in school in England we were taught about Indian, South African and North African history - granted, as it related to England and to some degree, the United States.
But to respond to the question - I agree that a white history month is unnecessary.