I agree totally. But it is a two way street for the kids and coaches. If the kid wants to get better, he has to listen to constructive criticism. If the coach wants the kid to listen, he has to present his criticism in as positive a way as possible.
Parents who allow their kids to disrespect their coaches are part of the problem. Little Johnny Do No Wrong needs his tail tanned at home, instead of having mom and dad telling him to not listen to him.