Also why is ecological footprint even important itself? Our eco system has no more reason to exist than any of its components, including humans.
Also, have fun not having anyone to take care about you when you grow old. And your retirement won't be worth shit either without a new generation to keep the economy going.
Yeah no thanks, fuck your anti-natalism. You might as well remove your own ecological footprint if you would deny your children's their existence for that reason.
What I would like to see is a norm on numbers of children. Personally, I think that having more than the replacement number - i.e. more than 2 - is straightforwardly unethical given the stress our planet is under. But by the same token, 2 or fewer is fine. And it would be nice if those who choose to have none got a little more respect for it.
We also have cultural pressures, which can shape individual behavior. We could have a culture where the default is not to have kids, but that you should not have kids unless you are stable and secure enough to have then and are prepared to invest sufficiently in raising them.