Read what I posted before. The extent of gear you wear will affect the way you ride, because it helps add to that "I'm invincible" feeling kids have. If they don't wear too much gear (and remember I still consider helmet, gloves, and boots to be almost mandatory) then they will tend to ride more conservatively, especially if they are told some true stories of people who have crashed in the past. Then, as they graduate up into faster and more capable bikes, they will have established safer riding habits and skills, that will make them less likely to crash. At that point, more gear can (and should!) be added to protect them against the increased risk of having a higher-performance machine. That way, in adulthood, an off-road rider will have a skill foundation that emphasizes caution, safety, and respect for the dangers of riding, but ALSO have their suit of armor.
The reason I think this, is that I grew up riding with short-travel suspension, and that increased my risk of being injured when riding. So to compensate for this (which is an automatic subconscious process) I paid extra attention to clearing obstacles and focusing on what I was doing when I rode, because if I messed up in that regard, I knew the back-end hop like a cougar and throw me into the wilderness. Then, when I got my Husky with long-travel suspension, I had the obstacle-avoidance instinct and skill that allowed me to either avoid potentially dangerous obstacles, or be so prepared for the "fatal" impact that everything works out. I think that a similar approach can be applied to safety gear.
And once again, this applies to those doing off-road riding, not motocross, not freestyle, and not anything else that requires you to put yourself "on the edge" in order to perform successfully.
