When you start poking around parkour videos, you'll start to see a trend of people wearing extremely baggy pants, often with the crotch hanging down to about knee level. This is particularly odd to me since you'll also find references to using duct tape to tape down baggy clothing to reduce air resistance, specifically taping down the cuffs to keep from tripping on them and to keep them from catching on obstacles.
The closest I've found to an explanation is this article, which posits that it's a combination of follow-the-leader (everyone else is wearing baggy pants, so it should be good, right?), hiding sloppy technique (baggy pants hide the fact that your legs aren't quite moving together by masking the outline), and comfort (when not doing jumps, baggy pants are just plain comfortable).
So, is there any particular reason why so many parkour practitioners wear extremely baggy pants?