A good challenge for difficult planets would be an energy based enemy that can mess with your electronics and requires a certain type of material to craft into a container or weapon to kill (maybe they could be used as a power source) Feel free to add on or point out issues with this idea.
I like the idea to use them as power sources. Maybe if you can tame them you can use them as living batteries to bring electricity to your house (or maybe you could use them only if a blackout happens)!