Overpopulation can be an issue. The ratio of people to available resources is crucial. Once there are too few resources for a population then poverty will become a tremendous issue. Resources like water and food are often scarce in third world countries. This leads to so many other problems. A lack of education then contributes to families in poverty having way too many children. Infant mortality rates than shoot up.
A nation should always strive for growth. When a nation gives up on growth, it is basically giving up on the population. My my question would be, is the population's well being is important enough to continue to put forth effort. Of course the population is important, so one should continue with the population's future in mind.
Growth is the mantra that drives so much of the development in the world, but at a certain point, the quality of life and progress is about being sustainable and responsible and not so insanely focused on growing. Growth in the extreme is just greed. There should be a point where nations focus on quality instead of size and power.
It's not hard to understand human nature. As said in The Matrix, "Humans are Parasites." Nations won't stop growing. And, that could be a good thing. More development. They would need a way to expand. Space, perhaps? Quite possible. More Development, more cool stuff for the nations of good old planet earth!