(answering without research) Power supplies, i.e. the battery problem. Wheeled vehicles are much more efficient than walking/running. So for an exoskeleton yo

(answering without research) Power supplies, i.e. the battery problem. Wheeled vehicles are much more efficient than walking/running. So for an exoskeleton you need more motors, you need big joints, AND you need a bigger energy source, whatever that may be. My guess is that batteries can't meet the cost and weight requirements, and there is no market for a 1000 lb. V8 powered wheelchair that would probably kill 3 people if it fell down the stairs, negating the benefit of the extra mobility.