[Mary-Jane]

> Due to some [reason], an overpopulation calamity hasn’t yet happened and we might coincidentally stabilize at a level that’s somewhat close to what maximizes average utility...

Given the birthrate trends in developed countries, it's more likely the population will peak and then decline as prosperity spreads. The cause isn't hard to discern - child labor laws - they turn children from potential assets into guaranteed liabilities.

A declining population will be a bad thing; our modern way of life is built on systems that depend on growth (from Wall Street to our tax structures to the various Social Security safety nets countries have in place); take that away and we will have real problems.