It is also a survival imperative to eat, but we have no problem dieting eh?
We have learned that what is good for the whole is not necessarily good for every individual, but we haven't applied that to parenthood. We can encourage parenthood among those who are good at it [financially and emotionally stable], while discouraging it for those who don't want to be parents. Doing the 'right' thing [having children] for the wrong reasons [because 'it's expected' or 'the Pregnancy Resource people made me feel guilty, so I had the baby'] often ends very badly.
Survival of the species is not threatened by women who don't want children or by gay people, any more than by people [and here, I think women are the majority] who kill their own children. Our lizard brains don't know that, but there's no reason to pretend that we don't.