This seems somewhat related to the argument Robin Hanson once made that any creatures that can pay for their own existance and would value their own existance should be created.

This seems problematic if when designing minds, in particular minds that are prone to excessive pain and anguish, one could specify, as an additional fact about that mind, that it would value (act to promote) its own existence.

There are also issues if a different creature/mind could be designed to better fill the economic niche, that produces more surplus in paying for its existence, that values its own existence more.

Consider the creatures you would design to perform the function of the house elves, and what are the reasons that house elves are different that this.