Of course, all the bishops had to do was say "no" as well. Instead they said nothing at all or at most sent the abusers somewhere else. But its God's will those bishops were there and who are we to question him, right? One can't expect the Pope to get involved, either- he's too busy worrying about important things like people using condoms or a few hundred murderers being given the death penalty.
And no, these boys weren't all 16 or 17; many were 13 or 14 and kids that age are generally completely sexually inexperienced and very impressionable. I'd say a 30 or 40 y.o. priest who is in the position of authority has the greater responsibility to behave himself.
Finally, to put masturbation, pre-marital sex, and birth control in the same category as statuatory rape is completely absurd. Adultery is a darker shade of grey but at least the participants are adults and know what the stakes are.
It's all mortally sinful i.e. cuts us off from God's grace. Both the priest and the teen ager is cut off from grace. Both need to confess their sins. It's all about grace. Everything is grace.