Oh? Not sure Ive seen these common usage. Any pictures?

Do a google image search for spinners and you will find 10,000 images of bags sitting 2 or 3 inches above the floor, with wasted space between the 4 wheels.

Why talk about pockets, hard side soft side, etc etc? Just look at the single feature and evaluate that.

Oh, I do have an old samsonite hardside roller- and it sits an inch or two lower than modern spinners. Thats an inch or two more space INSIDE.