Couldn't the whole "ethical teachings" some martial arts schools offer muddy the water a bit? Could a student hold back from using their training when they actually need to use it because "Sensei told me not to" or "I must follow the way of the warrior and refrain from violence". Couldn't the whole dynamic of telling your students when to use their training/when not to use their training inhibit your students ability to think for themselves?
Personally speaking as an adult, I'd be highly alarmed if a person I was training with was getting their information on what was right and wrong from a guy with fancy pyjamas and a black belt, or some guy wearing a Tap Out rash guard. Adults should have enough about themselves to know right from wrong without being told. And as for kids, surely Ma and Pa should be helping them calibrate their moral compass, not someone, as Cord said, they see a couple of hours a week in a martial arts class.
"Let your food be your medicine, and your medicine be your food"