Comment by runarberg

I think you have to be pretty used to visualize volume before it becomes easy. I think having the unit based on a cube still helps though, especially since you can pick a different sized base cube based on the scale (mm³, cm³, deciliter, liter, m³, km³, etc.), having the base unit be this extremely low, and wide rectangular cuboid only aids in your visualization in a very specific context, namely how how many foots you are flooding your acre sized fields with water.