Mortons,
The problem as I see it is two-fold.
1. At the age your son was injured, some boys are hitting puberty, some are not. You can have some lads who have hit their growth spurt and are really starting to gain mass playing against kids who are still every bit little boys. But this was not such a problem until...
2. The equipment changed from what it used to be. When I was 13, some 30 years ago , the shoulder pads were just thin little bits of quite flexible plastic attached directly to just some felt pads. The elbow pads were more like what you'd wear today to go out rollerblading, no plastic, just leather or vinyl over, again, some felt padding. The equipment was as likely to soften the impact to the receiver of the hit as it was the deliverer. You had to be tough and more important, skilled to really hit hard, or you could get hurt just as bad as your target.
Today, those shoulder pads are great re-inforced orbs of thick rigid plastic suspended from contact with the wearer by a system of taut internal straps, the elbow pads are the same way. You could smash your elbow repeatedly into the boards wearing those things until you make a huge dent and never feel a thing.
The parent may feel their child is well protected, but too much of the risk of delivering a hit has been eliminated, transfered to the target.
How do deal with this? I have no idea. Except to say that the no hitting from behind rule is a good one, and needs to be rigidly enforced. Intentional boarding, which has always been on the books, should be a suspendable infraction in all junior leagues.
I'd love to see the hockey equipment at all levels of the sport go back to the state they were in when, say, Gordie Howe and Jean Beliveau were playing. Those guys were not only damn tough, hard players, they had to respect each other because they weren't swathed in equipment that could withstand a good crack with a baseball bat.
Eric