I think it's silly to state that Johnny being a blonde haired, blue eyed white guy isn't essential to his character when every major AU version of him has retained that look. So will it be okay for White/Asian/Spanish guys to audition for Blade if another movie is done? His identity is just "vampire hunter". How about Luke Cage? There are tough non-black guys in Harlem. Their being black doesn't seem any more vital than Johnny's being white, but I guarantee the reaction wouldn't be the same.