I really identify with some of the points he's making, they're observations I've made myself so it's nice to see someone with his clout bringing them up.

I wonder about the design thing though - our code is in some ways a document of the circumstances surrounding it. Does it make sense to have it conform to some Platonic ideal, which we corrupt when we alter it to make it more testable? I'm really not sure about this, but I doubt it. Code ultimately needs to work in a given set of ways and that's our primary concern with it. Making the code "pure" (or just "easy to read" if you like) is a service to other developers who come along later. So, the tradeoff is testability for intelligibility. I can imagine a lot of scenarios where that tradeoff is a rational one.