[Jack Simth]

There is some advantage to a set of legs and arms on a battlefield:

Bad Terrain:
A man can climb a mountain. A horse, not so much. A car, even less. All land-bound military vehicles have some kind of terrain they must avoid; legs have less issues with many types of terrain, especially when they have arms capable of carrying the weight to suppliment on occasion.

Piloting:
There's less re-training to do when the machine is reading your motions directly off your limbs, and duplicating them near-exactly. In a car, tank, or aircraft, sure, you get the hang of the controls fairly quickly, and in not too terribly long, the vehicle is almost an extension of the driver - almost anyone could be walking around in a proper powered suit in no time flat. Shortly thereafter, dancing.

Moving Stuff:
Occasionally, awkward stuff must be moved. Sometimes, this must happen under fire. A good set of powered hands would do wonders for such things.