Parents asking for the "plan for their son or daughter" is not questioning the coach...but is the only way that this thing can work - if the parents are not supporting the coaches decisions at home then the kid will be getting mixed messages.
In order for parents to be able to say "do what your coach says, work hard, be enthusiastic, don't eat candy and drink soda and stay up late at sleepovers, keep up with your school work so you don't have to miss practice, skip that birthday party to go to that meet that you KNOW you won't score great at, etc..." we need to be on board! This is an expensive sport and requires a great deal of dedication. I would expect the percentage of high achieving type A parents is a little on the high end, too....which means we WANT INFORMATION!!!! But most parents whose kids stay in gym more than a few years learn to trust the coaches, learn that their wonderful child has strengths and weaknesses, good years and bad years...etc. And we see the other kids at the gym too, so we can "judge" coaching decisions with regards to more than just our own little stars... if we feel the need (and who with a child doesn't want to be wise about the adults in that child's life?).
At work I often spend far more time explaining what I recommend with this SE class of parents (and face it, gym is so pricey the SE status of most families is middle and up)...even though I have 11 years of medical training and 16 years of experience - I still have to DEMONSTRATE that knowledge and be willing to communicate. I understand that this may not be most coaches favorite part, or an area they are skilled in - but if you work with kids you work with parents and need to be willing set aside time to communicate.
Coaches absolutely should set the rules as to how this communication occurs - no curbside "why isn't Suzy doing her kip...". Some parents just won't ever get it...but most will and then can be an active part of the team - the coach is not there for 20 of the 24 hours a day, you know!! For instance, a coach being misunderstood by a child about top scorers can be easily rectified if the parent has already discussed the coaches plan for the child...the parent can guide the child to get clarifications, and help to maintain the child's trust in the coach...