RTD threw Martha and Mickey together for no other reason than they're black.
As stated though, racism rarely bothers me and I find the idea that races compete with eachother in the Offence Olympics as to who suffers the most injustice to be hilarious. I heard a recent interview with Jamie Foxx where he claimed there was "nothing in the world more dangerous than being a black man in America today".
Get perspective, people.
Oddly, I almost NEVER hear complaints that Chinese people aren't portrayed well in Doctor Who, despite them easily having the most legitimate case. We've had 2 black companions in the modern series. What the fuck more are people expecting!? What do the black community feel they're still owed? 3 black Doctors!? No other minority community whines this much, despite them getting FAR less exposure in the media. When was the last time you saw a Native American headline a blockbuster movie?