You have just hit on actual casting racism. They will cast someone Black before anyone else most of the time. Having Rani(a Indian) in The Sarah Jane Adventures was refreshing for the fact that there are many of that ethnicity in the UK, and Doctor Who(and most television) tends to ignore them. I was ecstatic that they cast her. Here in the US, they will cast someone Black before they cast a Hispanic, despite the fact there are more Hispanics than Blacks living here.
What the *beep* are you talking about, their has only be 2 nonwhite actors who have been companions 3 counting Micky so that somehow equals to hidden racism considering 95% of the cast, the writers, the producers and executives have been white.... Most of the companions have been women so do they hate men, that's how stupid your question sounds!