If they cannot be trusted, why would you use them in the first place?

For the same reason you'd build a fire.

Obviously people perceive value there, but on the surface it does seem odd.

"These things are more destructive than your average toddler, so you need to have a fence in place kind of like that one in Jurassic Park, except you need to make sure it absolutely positively cannot be shut off, but all this effort is worthwhile, because, kind of like civets, some of the artifacts they shit out while they are running amok appear to have some value."