Something obvious occurred to me just now. Bows send arrows in an arc, thus archery. Therefore, having their range converted from yards to feet underground makes perfect sense. Crossbows are favoured by underground denizens because quarrels don't arc - they depend on a relatively straight trajectory, more like a firearm. Therefore, crossbows should get to retain their range in yards underground, thereby conferring an appropriate reason to select crossbows for dungeon situations.