As a black person, speaking just for myself, I really do not get the issue around semantics like this. The word "Master" is not synonymous with any race and so does not make me (or anyone I know) uncomfortable. The concept of masters (and slaves) exist and are useful metaphors for naming similar phenomenon. I would much rather focus on issues that make people truly less comfortable in technology, like hiring or sponsoring practices in organizations. If there truly are (black) people offended by this nomenclature, I would not oppose changing it but I honestly don't know any.