Opti sailing is one part sailing, one part baby sitting. Parents get kids into Opti's to teach them to sail, but its also about giving them something to do, keep them entertained, and let them enjoy the water for a couple of hours. Opti's dont go very far, or very fast, so its easy to keep an eye on a bunch of kids in boats. Its the YC parents that want the kids out of their hair for a couple of hours, and its what they started in, so they have to put their kids in it.

If you gave them waves, they'd be all over the place in no time.

I can think of 10 boats better than the opti for learning to sail - sunfish, tanzer16, 12',14' or 16'catboat, etc

My daughter is going to learn to sail on one of these
http://www.by-the-sea.com/areyspondboatyard/apbycatboat.html