Oe might be, is this kind of thing healthy for individuals, or society? Not only in terms of the health of the body, but psychologically, and also socially.
This is how sex used to be looked at - as something where people could behave immorally, exploiting the vulnerabilities of others, or using them as an end for their personal pleasure without any more permanent or deep connection or responsibility attacked.
We very deliberately jettisoned these ideas though, and made consent the only metric. Some people might also include direct physical harm, but even there it can be a struggle now to draw a boundary.
The problem of course is that if we considered these other kinds of principles, it might impact how we look at things like anonymous sexual encounters/one night stands, kink, sex clubs, etc. And that's just prudishness, right?
So we are left with consent. And it's already well established in law that animals don't need to consent, so this is on the table, just like sex work of various kinds, bdsm, polycules, etc.