tl;dr appreciate your own mortality, be mature about progression, and you will enjoy life for longer
okay, just streaming thought here:
Pain - Fear - Progression --- it's a loop whereby you can't have one without another. But I don't think a person needs to get injured to progress, in fact I think that an injury just slows that loop down or stops it completely. So if you get too injured, you're not even going to be skiing anymore and then there's time to be thinking about what went wrong: and there should be a benefit in that self-reflection so it doesn't happen again. (personally I suspect a lot of people are getting injured nowadays because of weak bones due to health and nutritional reasons)
Also, some people are immune to pain and fear and will just progress (assuming they are very coordinated) until they push themselves, the entire sport, or die, or both. But if people are immune to pain and fear and want to progress themselves or the sport, and are simultaneously uncoordinated, then they will find injury quickly.
But wearing your injuries as a badge of honor to me is a somewhat retarded exercise unless you fully recover. Although, being proud of one's injuries might also be a coping mechanism in order to avoid ridicule, or give life meaning.
Anyhow, there's a nice vid of Mr White here just chipping away at different parts of the bowl at Venice Beach (sick fn' bowl btw.) Doing controlled bails, single trick attempts and just learning the bowl. In the end he starts to link the tricks up. If he was injured, he wouldn't be doing that.
So I think the key to progression is incremental improvements and controlled fails... not through pain and injuries. Reinhold Messner the mountain climber said that the key to his success was that he failed the most. Glen Plake once said in the early 90s that he looks for mature skiing (that was when everyone was calling it extreme.)
Personally I used to get knee whip a lot. I overcame that with a custom ski but for a long time I used to only ski half-days or mornings. Right now I am experimenting with crystals so I can balance out feelings of fear and euphoria (how easy is to get injured when you're feeling on top of the world and invincible?) Also, something as simple as good bodily protection respects one's own mortality.