Most wheelchair users are either elderly or suffering from some other deteriorating condition associated with pain, overall weakness, or instability, and will therefore likely not be able to use these. (Note that even in the promotional images, people are using crutches to balance in addition to the exo-skeletons.)

The classic "strong above the waist, paralyzed from the waist down" image of a wheelchair user that people might have from eg the paralympics is the minority.