Should is subjective. The origin of the system is from how the wires are made.

You can make a wire but draw to conical holes that rescue the wire size it is called,https://en.wikipedia.org/wiki/Wire_drawing The wire gets thinner and longer in each step.

The AWG system is based on the number of times you draw it through a die to get the wire.

Each time you draw it in the system the diameter reduces to 92% of the previous.

​

I am not sure why the system starts with a Nr. 0000 at 0.46 inches in diameter and end with Nr. 36 awg at 0.005 inches in 40 steps and not 1 to 40 but that is the way it was done