Are you talking about geographic mapping? Or organizational or process mapping?
The first one should be obvious... In order for a society to grow well, it must be well organized and every aspect of ow it operates must be structured.
Without mapping, well how can you run a country without knowing how to get around from a to b?
Things like supplying, logistics, trade, defense.. All sorts of things rely on having an accurate understanding of the land around you.
For an in-depth read, here's this file I found: ies.jrc.ec.europa.eu/uploads/SDI/publications/EOBenefitWS_JR
As for process mapping, it is always good to have a structure to how decisions are formed and how action is taken, and the ability to retrace steps, analyze decision making and what not...