Power-Law World is the notion that, in the ancestral environment, the possible outcomes were basically normally distributed in terms of available utility. Therefore, our intuitions are shaped for a world in which outcomes are normally distributed. It isn't worth exploring too much, because dramatically better outcomes simply aren't available. 

In contrast, the modern world has many orders of magnitudes of differences in outcomes. The CEO of a large company wields millions of times the optimization power of a subsistence farmer. It is worth attempting to update our motivations to reflect this, even though we will most likely fall short because System 1 can't do math.