Let's go over the reasons for imprisionment again:
Punishment—Simply, "tsk, tsk, don't do that again." Frankly, a bad justification, as we are not three-year-olds.
Deterrant—Obviously you ain't doin' a good job of deterring people if you cannot trust them to not do it again!
This country really needs to take a long, critical look at its attitudes and policies towards sex, violence, punishment, love, drugs, and everything else. I pray we can get at least one slightly more sane law on the books from it.