Also, the way that you apparently like things, because it is ad hoc, has the "draw problem", where you think that you're telling a shape to draw itself on the screen, but actually you've told your robotic cowboy to shoot your friend in the head.

I know that many people think that this is not a problem worth worrying about, but I think that in a large program it is. Accidentally calling a method that means something completely different from what you thought it meant is much less of a problem if you have to explicitly import the interface that the method you aim to call is supposed to be implementing.