It's very simple to understand that if you increase the opening you would have increased airflow through the radiator resulting more stable coolant temps and less drag from your fan clutch. In hot weather the car can maintain temps but the engine and fan has to work hard at it to pull air through such a small opening.
My post has nothing to do with how the cooling system is working on my car. I was simple pointing out some functional pros and wondering what people think of it's cosmetic appeal.