You make a valid point. Some coaches aren't so good at taking input from "stupid parents". I guess approaching the coach with something like this is largely dependent on the coach. From my point of view, as a former all-star and TB coach, I made an attempt to stay out of the way of the instruction players were getting from paid instructors - whether I agreed with it or not. In those situations, I focused more on mental approach.
We can only wish there were more who take this approach...maybe a "DFP Good Coach Clinic" should be held along with the pitching, hitting, catching clinics! ;-)