Agreed,
Every now and then, while teaching applications and real-world self-protection, I make sure to remind my students that one of the best techniques to know is how to turn and run.
One of the 'codes' I used to have to repeat at the school I came from was "No Retreat In Battle". I always disagreed with that completely. I want my students to live. Sometimes your opponent will be armed or there will be multiple opponents or your opponent may just have the upper hand. To quote Master Jay S. Penfil, "I'd rather hear you tell me the story of how you got away then hear from your parents when the funeral is going to be held". Honor and standing up for what is right is truly important, but so is survival.
So then why do we teach any weapons defense? Because sometimes you're not going to have the choice to run away. You may be cornered, you may be taken to close range before you had time to react, there may be someone else for whom you are fighting and retreat may be at their demise... That list can probably go on.
Everyone should know defense and protection techniques. Children should know defense as well. But teaching knife and bladed weapons to children can be dangerous and must be done thoughtfully by the instructor.