everyone can have their own importance mix for sure. Someone could find Anchorage, Alaska the most important ( and I say that without irony ). But if you want to talk to other people and use the kind of shorthand that all people understand very quickly, then GDP and population are pretty good indicators of importance that everyone sort of agrees to use as the proxy.
I'd say that cultural and political significance, while not as straightforward/objective to judge as GDP/population, are very much factors that are/should be in the layman's shorthand.
yes, but "cultural and political significance" are hard to define and so two people could easily talk past each other, because they would define these differently
whereas gdp and population are
a) easy to define and
b) correlated with significance
