I don't think that being on the registry is considered part of the punishment. It is a reflection of the concern about recidivism rate among predatory sex offenders. The same recidivism rate is not found among murders and so it is not felt that a registry is needed for them.
I see more of a problem with who is labelled a sex offender. For most the term "sex offender" bring us images of child molesters and rapists. While they are a valid concern, there is a whole range of other people lumped into the "sex offender" group.
*** "was a 17-year-old pupil getting top grades and showing enough promise as a footballer to catch the attention of Ivy League schools. Popular among students and teachers, he was voted Homecoming King, an honour bestowed on a star student or athlete.
Today *** is two years into a 10-year prison sentence for having consensual oral sex with a 15-year old girl at a New Year's Eve party three years ago."
This guy too will be on the sex offender registry along with rapists and child molesters.
I knew a guy who bought his son a prostitute for his 16th birthday. That act landed him on the sex offender registry and he wasn't even the one having sex. While his judgement could be questioned, i have to question the value of lumping him in with rapists and child molesters.
There was a case a few years back of two kids sending each other nude photos of themselves on their cell phone. The photos came into the hands of the authorities and they were charged with producing child pornography, which landed them on the sex offender registry.
Many of the people on the registry are not rapist, child molesters or predatory.
While there may be value in tracking predatory sex offenders, the current habit of lumping all sex offenders together would seem to dampen that value.