I don't know about you guys, but I am not going to spend $3,000 on a light weight(50kg) foam core boat(read fragile) to give to my kid so she can go run into or be run into by other kids while learning to sail.This will happen. Lots of money or my time to fix.
For kids 13 and under the Wave(or similiar roto-mold durable boat) works great. After that they can sail whatever they want.
Having a kid on a trap wire is great fun for them and sometimes scary if your not careful. It's a big jump for the kids to skipper the boat from the wire not to mention the danger of having a kid sailing by themselves and hooked into a trap.(they have a tendency to bare away as they jump out)
I have 3 kids worth of experience with all of this. The big thing is to just get them and as many of their friends on a boat as you can and go sailing. They usually want to stop and swim or drag their feet in the water or lie down on a hull and drag their arms and splash whoever they can.
It seems your thinking to much like adults and not like a kid(7-12) would.