What Polanski did was sick, twisted and despicable.
My opinion.
In my opinion, it was despicable what he did. and deserves some legal punishment.
But it was more of a jailbait scenario, rather than the kind of forcible kidnap/rape of a virginal pre-pubescent child that really deserves much more extreme punishment.
There are gradations, and extenuating or mitigating matters when it comes to human sexuality, that would make each case relatively more or less of an affront.
A large percentage of Americans have sex before the age of consent (average age is 17).