There are policies from 600 years ago that are in effect and beneficial. Like the Magna Carta [0], which was 800 years ago, and its derivatives.
I do think my original point still stands that we seem to be quite bad at making good decisions for more immediate generations. Considering our rather pressing current challenges (climate change, continued warfare, etc.) I'd settle for getting the next few generations in a better place before thinking about 25 generations from now.
For South Korea specifically, the population challenges are probably more immediate than other countries.