Wheels continue to support a load without power. Wheels are vastly superior to hover technologies in the crucial areas of steering and controlled braking. (For

Wheels continue to support a load without power. Wheels are vastly superior to hover technologies in the crucial areas of steering and controlled braking. (For uncontrolled braking, you just cut the power to your hover fans and lift the skirts...) It turns out to be remarkably difficult to get a hovercraft to go up an incline... Wheels are both suspension and traction in one system. There's no particular physical advantage to JPEG over the others mentioned; it's just currently ubiquitous.