"Harness leather burnishes wonderfully, raw edges aren't a feature, it's laziness."
Incorgnito makes a point here. It does burnish easily giving it a worn look. But so does latigo leather and bridle leather, both good choices for making comfortable belts. Harness leather was likely chosen here for its tough wear characteristics. It's often used for gun belts which must support firearms and holsters as well as other accessories. Some of them are near a 1/4" thick which doesn't make for comfort. But,again, I'd prefer a belt where the leather craftsman finished with a beveler to smooth off the edges.