See again we seem to be looking at the same thing not seeing or hearing one another. I never said anything about not turning the sholders or even the hips for that matter. Just the angle of the fist kick in a double. Even on triples you need to turn the hip and shoulders but the angle of the first kick is always a the lightest the lowest and most times at a 45 or even straight up and down (front kick). Think of it as a starter kick or primer kick. It is not your intended scoreing kick. Not every technique will land nor should you try to make every technique land. Now you can do that on someone that is not any good, yes.
I know exactly what you are talking about. You are not the first to say go 45 on the first kick on double kick or that you should aim it below the waist. If you want to do it that way, go ahead.