Your argument generalises nicely to almost any crime.
No it doesn't.
Yes it does. You've presented a valid difference between abortion and rape, that victims of rape can decide for themselves and victims of abortion can not. But that difference does not affect the generalisation.
Your initial argument
* demand for abortion will always exist
* illegal abortion is dangerous
* abortion can be made safer via legalisation and regulation
The same argument for rape
* demand for rape will always exist
* illegal rape is dangerous
* rape can be made safer via legalisation and regulation
The will of the victim is irrelvant.
Obviously I'm not saying that rape should be legalised, just that the "legalisation will make [insert controversial issue here] safer" argument alone is absurd. Safety clearly isn't the only factor (if it was, then rape should be legalised). There are moral factors on which nobody has an equal frame of reference and consiquently on which nobody can agree, which is why the abortion debate never ends. It's a foolish waste of time to continue debating the issue without realising this simple fact.