There is something about your society that you like, else you would be somewhere else. And, bluntly, if your society doesn't make babies, today, then in 20-30 years time there won't be people brought up in this culture. Either your society will go into decline for lack of said people, or will rely on immigration (assuming it's attractive to expats), eg people with different values to your society's.
It's not saying one society is better than another, only that if you think there is something good about your society (liberal rights? nukes? hell, maybe you're North Korean and like dictators!) then it takes babies to sustain it.
The default is you will get people brought up with values of most populous societies, which may or may not align with yours.
This is a line of reasoning I don't get. I mean I understand it, I just strongly disagree.
Countries are made up of people, individual people. How important is it really that a country is a "superpower" if the average person eeks out a horrible existence. To take it to a further extreme, look at the Russian empire of the late 18th/early 19th century. Russia was definitely a Great Power at that time, while also the majority of the population were slaves (there really wasn't much of a difference between serfdom and slavery) who were borderline starving, or actually starving, during that time. But rah rah Russia definitely got some nice palaces out of it at the time that certainly make great monuments today.
I'm much prefer to live in a "non-superpower" with a much better quality of life for me and the people I love.