I might be being a snob but if you haven't passed Pre-Para or P-Coy then you can't wear wings... As to a PTI/PJI having no problem passing Pre-Para... You might be right, (it's easy to run alongside a man carrying 50 lbs and a rifle in boots though), but let's see the same people pass Pre-pre Para - it's a different animal altogether.
PJI's wearing wings is just another manifestation of their fixation with mirrors...