The OP suggests a sort of dichotomy between 1.) worlbuilding that directly serves players and 2.) worldbuilding detail for it's own sake/for the DM/in case it's needed. Maybe you're suggesting a third type, worldbuilding that directs the type of gameplay that's supposed to happen in a setting--which, potentially, helps the DM keep focus and, even if it doesn't immediately serve the players, could be expected to as a game progresses. This is something I should probably think about to do worldbuilding better.