One of the many issues in diversity in MU*ing is the setting.
Here's a WoD/CoD example:
Yes, there are Black people in New England, but when every single game is set in Small New England Town, New England State, it is a reach to figure out why my Black Vampire/Mage/Changeling/Werewolf is in this area. Everyone has to come up with reasons, and I have. But knowing that realistically my character would, at the very least, stick out in a crowd, makes upholding that IC Masquerade difficult in Small New England Town.
Sure, put your game in a place that you want. But when you look at the character roster and it looks like the campus of BYU...maybe it's your setting.