They have them. A lot of the more-substantial armor is still an undergarment, though. It can still also cause significant layering issues of it's own, because it can get hot.
For Bushwhacker, I didn't know the circumstances of your Dad's accident, and hope I didn't seem insensitive in talking about Leatts. My point is, they actually do work for what they're designed for. now that they exist. (I was skeptical when they came out, because of the way helmets and knee braces have been promoted, but unlike for them, for Leatts the stats are meaningful). They're actually not even all that cumbersome. So it's very rational to wear one if one is concerned about that type of injury risk. Sports with significant injury risk tend to have an awareness of both the risk, and ways to mitigate it. Hence moto or bmx and use of Leatts, now that they're available. (They also don't mitigate all risk, obviously, and for things like XC mtb would imo be too hot and constricting).
While patrollers certainly see their share of life-changing spinal injuries on ski hills, the risk to the average Joe or Jane of head or spine trauma is so low that there's very little awareness of what the risk is. So they have little awareness of the actual protective gear that's out there. This is reaonable. Most people are at more risk of a head injury at a summer backyard pool party than they are skiing, and they don't helmet up at the pool. But there is also great awareness of a quasi-moral "need" for one type of gear that's very visible and so fashion-based -- helmets, versus shinguards, spine protectors, Leatts, etc. etc.
Telling people they should wear less protective gear can be helpful. If I show up for a MTB epic on buff singletrack wearing full DH armor, you'll think it a little odd, and if I hold everyone up because I'm suffering heat stress 10 minutes into the ride you'll likely be even a little annoyed. You might then tell me to wear less ch*t. If someone shows up for a backcountry ski tour wearing a Leatt, I'm not goin' with them. Sidecountry, maybe, but they get listed as a gear freak in my mental book.
wouldnt you need a full face helmet to use a leatt? I guess the fact that a full face helmet can torque your neck would go down alot with the leatt.
trust me I do wish that the leatt was around and being used by my dad 16 years ago. My life would be way different today if that was the case.
The points you make about someone showing up with gear that hinder them(IE full body armor on an epic ride), where as a helmet really doesnt hinder anyones skiing.
one thing about visiting my dad in rehab as kid was realize how much worse it could be. meeting someone who has had a TBI will make you sad almost no matter what. spinal cord injuries are lucky compared to severe TBIs.