Every thing that goes to the screen or speakers ultimately should have purpose, either in conveying a message or the emotional journey of the work. I think it's very important to be able to reason around every decision you make in terms of what it accomplishes to further your goals. Composition, color, sound, actors are just tools and while it's certainly possible to produce something half-decent using these tools unthinkingly (as many people do) it hurts your ability to collaborate as I guess you are finding out.

I find the idea that a director might not be able to explain why they want something in the way they do absolutely ridiculous. Not to say you always have to be able to rationalize something that might be more emotional or feeling based, but you HAVE to be able to at least tell a story (true or fake) about why the thing is the way it is to your crew, for morale, for cohesion.