In absolute agreement WhirlyBird.
Teaching someone anything is all about communication. Aircraft are machines, as long as everything is working properly it will do exactly as commanded. People are not machines, even if everything is working properly they will not necessarily do exactly as commanded..if you get my drift.
Imparting the knowledge is a much understated artform in my opinion. Effective instruction is as much about having an intimate understanding of the human condition, as having the same understanding of the machines that we fly and the environment we fly in. Your basic FIC does not address this.
At all levels in flight training and beyond, it seems that PPLs, CPLs, FIs etc. are given the bare minimum to get on.....the rest is down to as you say "maturity and judgement" and a dollop of common sense.
All good stuff....