This is a difficult situation. On one hand you have those that need to be locked up, and kept track of. Anyone that is old enough to know the laws, should have their names on that list for any sexual act without the consent of a partner, or where consent can't be given. This should be for any, regardless of age.
But there lies the problem. We educate our children young that killing each other is wrong, that stealing is wrong, but we shut up about what is right and wrong about sex, other than rape. The government places laws in place, but neither the schools, nor the parents are willing or able to teach young teens, due to many different religious, ethical, or what have you hangups about talking about sex with children that are physically able to break those laws.
The registry is there for a reason, and the reason is a valid one. There are loop holes, and it can and has been abused. But it would be better to force education at the proper age, then to change the laws that are in place at this time. It would be easier to teach not only anatomy, but the laws, local and federal, that are in place and the reasons behind it, than to change the laws that are there regardless of how ancient and out of date to current society.
I mean, you take a course in driving before you can get a license to drive due to the dangers of, why not sex education and corresponding laws? It shouldn't just be about anatomy, but the laws that are in place for protection. It would stop some of the problems of teens into adulthood with things that to them seem to have no consequences, by giving them the education they need. There would still be some that would do those things anyway, and then there should be punishment. But for those that don't know the laws, can you really say that they know the consequences of their actions? That they are knowingly doing something wrong?
My children are still young, but I plan on educating them on what I can as they begin to reach that age. My oldest is extremely shy, but even her doctor said that it is better to educate her about her body (ie. her body changes as she reaches puberty) before she reaches that time. I figure the same applies to sex, education, and laws. Teach them early. It doesn't make them promiscuous. I learned about sex early, way too early, but I didn't become active until I was 18, even with the opportunity. Once of age, I used protection until I was willing to deal with the consequences. I didn't because I knew the consequences. I wasn't willing to lose my freedom by getting knocked up, getting some disease, or making someone go to jail because I was jailbait. My mother made sure that I knew from her experiences, what were the consequences of being active early could mean. I didn't want to go through all that. I believe most would say the same.