While I was traveling, I found the waist pockets on my J1TS-S really usefully for storing stuff. Because they wrap around to the back, I didn't have to worry about items bulking in the front. Also thought I lost my water bottle a couple times. lol
Additionally, the waist pockets have a small tab in the interior for your fingers to cling to. I might just be looking too deeply into it, but the pocket feels less like a bottomless void and like a more tangible storage space when you're resting your hands in there. Whether that was the intention or not, I was impressed by it nonetheless.