Yup, it's a pretty stupid question. Even in raw evolutionary terms, that's obvious.
You, dear human, evolved over millions of years to be deeply satisfied by creating and rearing children, watching them grow into productive adults.
This is perhaps the most fundamental evolutionary thing; most people will thus likely experience a good deal of emptiness, ultimately, without it.
"why even have children if AI and robots will do all the work?"
brother, the point of having machines do the work is that humans get to enjoy being alive and do what's fulfilling.
more time with your family, more things to create.
children growing up with possibilities that their parents couldn't even imagine.
how can you look at that future and decide the children are the unnecessary part?