If you traverse the cave tunnels often in the lower areas, this is easily hunting grounds. As a crafter player too, the amount of usable leathers, adrenaline, and morphine if you wander far enough, was more than ample/profitable, to the point in most of my games I often travel exclusively these tunnels when going around unless I am specifically hauling stuff to sell and am loaded.
With the addition of the deep caves in final release too, this might be more of a thing even more so, depending on what the environment is like/other additional tunnels to the ones we have. There does need to be some more dangerous wildlife, though, than crawlers. Enjoyed their challenge, but aside from them, the difficult wlidlife seemed to be few. Burrowers I do not really count, as their only useable thing being plate or poison, neither of which you need in huge quantities or even to sell imo. They are just difficult/costly to kill with no profit. And burrowers are not often in an easy to access area, for a variety of reasons. People gonna just cave in the area/path, or they are naturally isolated. Because, screw Burrower poison...
