Totally misses what ISO paper sizes are designed for, namely book binding and signature printing. That's why the scale-invariant approach is so important. Once you know how many leaves in a signature and what page size you want, it is easy to figure out which paper size you want to print on.
US paper sizes assume that you have specific design sizes to your printing technology (picas) and then give you a grid of an even number of those units.
Graphic designers / typographers I know tend to prefer the US paper sizes.
Regular people who want to make photocopies of enlarged/reduced pages tend to prefer ISO sizes.