Do you know how you make someone into a Dalek? Subtract Love, add Anger.
The Beatles were something everyone had in common; this was thirty years ago, there was Dr. Who and everybody knew who the Daleks were and there was The Beatles and everybody knew who George Harrison was.
The Time Lords really didn't like genocide. I'm not too keen on it myself. It's the potential you're killing off. What if, one day, there was a good Dalek? What if...