In most airplanes, there is plenty of room in the wings for more fuel. So as an aircraft designer, the path to maximum flexibility and utility is to make the tanks so big that the “full fuel payload” is little more than the minimum crew compliment. Then the operator has the greatest range of options to trade range for load.
The easiest way to maximize the full-fuel payload is to artificially limit the size of the fuel tanks.
There probably are operators (customers) who need to move a dozen people from Chicago to Detroit for a business meeting, and then back again in the same day.