I wouldn't dismiss the concerns of overpopulation entirely. Simple math tells us that, unless we are able to create a society with infinite resources (i.e. post-scarcity), it will always be necessary to make sure our rate of consumption is less than the rate of replacement.

So far, we are losing that battle, given the significant amount of non-renewable resources we consume at a global scale. On top of that, unchecked development which is needed to ensure that the needs of massively overpopulated regions are met endangers what few natural/renewable resources remain, which carries the threat of food scarcity, loss of drinking water, and permanent environmental damage on ecosystems that we depend on.