I absolutely love television, and I don't mean to be vulgar, but as I keep having to explain to people from the movie industry, I get more power and more money doing television, so why on earth would I do a film?
Steven MoffatThe trouble with a series as it gets older is it can feel like a tradition, and tradition is the enemy of suspense, and it's the enemy of comedy. It's the enemy of everything, really. So you have to shake it up.
Steven MoffatMadge: I don't know why I keep shouting at them. The Doctor: Because every time you see them happy you remember how sad they're going to be. And it breaks your heart. Because what's the point in them being happy now if they're going to be sad later. The answer is, of course, because they are going to be sad later. ~ The Doctor, the Widow, and the Wardrobe
Steven Moffat