Actually, most people recommend against substrate because it could cause impactions. Figure he aims for a cricket crawling around down there, gets some coco fiber stuck in his belly. He can't digest it, it starts to get plugged up, etc etc. Not only that, but it could cause bacteria to grow if you don't keep it clean. In the wild, the floor is generally turned up by so many other animals and humans walking around that bacteria doesn't have a chance to really grow, but in a small cage, with nothing churning it, bacteria can grow rather rapidly. There's also the chance of it causing injury to a chameleon. Rare, yes, but I do have a friend who would use substrate and found shards of plastic in it.
To answer the OP: crawling on the ground is normal. Kukui does "laps" around his cage - which involves crawling on the bottom every which way until he is sure there are no crickets in the bottom (which, of course, they are all in the top, in the corners, but he has yet to catch onto their sneaky ways).