I do understand this argument but those examples are very different.
Legalising a good is very different to criminalising a bad, because of the relative absence of unintended consequences and the relative ease with which they can be mitigated or safeguarded. Something which becomes legal, can be regulated.
For instance, to access legal abortion, a woman is counselled or at the very least contacts professionals. This helps to mitigate the unintended consequence of forced/coerced abortion. Compare this to the illegality of abortion and it's unintended consequences. Women still have abortions, only, they also suffer a high rate of terrible complications including death. In fact, this was probably the major component of the argument to legalise abortion.
Those who are criminalised, yet still motivated - will slip underground, out of sight and out of control.
Secondly, those law changes accelerated a process which had already started. The law came about because the tide of opinion had already started to change.
If you look at the population as a whole, we're more than ready for this practice to be illegal, the tide has well and truly turned and people are majority against. But in the communities where it is practiced, it remains (for the majority) very deeply embedded and non controversial. They are very far from ready to leave behind this practice, in my experience.
A law change accompanied by effective, very consistent enforcement might be effective but I simply don't believe that adequate enforcement would happen. Which would make the unintended consequences, proportionately far worse than any of the benefits, potentially for a long time or indefinitely.
I'd love to be wrong, because as I said, I am personally and professionally very against the practice.