In 'The Mark of the Instrumental', I argued that things (e.g. relationships) could have contingent non-instrumental value. This is because 'merely instrumental' values must be fungible, whereas contingent values need not be. In this post, I want to show that even if one accepted Keller's premise (ii) -- that we don't have any reason to create new relationships (e.g. between happy hermits) that would have no further beneficial consequences -- it still doesn't follow that relationships have merely instrumental value.
As it happens, I think (ii) is false: it seems better for people to experience meaningful human connections in their lives, even if the instrumental benefits thereby obtained could just as well have been gotten from (say) robots.
But even if you believed (ii), instrumentality still wouldn't necessarily follow. For it may be that even if relationships don't essentially add to the value of the world (independently of their good consequences), their loss (and replacement by an instrumentally equivalent substitute) would nonetheless be undesirable or detract from the value of the world. In this case they would have a kind of intrinsic value (being non-fungible and all), despite lacking what we might call contributory value.
To get a better sense of how this might work, consider the claim that Achieving X, where X is among one's life projects, is intrinsically valuable. Given that philosophy is among my life projects, it would seem odd to say that I should want to philosophize as a means to achievement. Rather, doing philosophy well would constitute achievement for me. And even if prior to fixing on this goal I might just as well have chosen any number of others, it remains true that I now have reason to care about philosophy for its own sake, and to be unwilling to substitute in some completely new project in its place. (Cf. inducing desire satisfactions.)
Now it seems open to one to say much the same thing about the value of relationships. Prior to having this kind of good life -- one involving meaningful human connections -- one might just as well have chosen a very different kind of life that would contain just as much happiness, achievement, etc. But it doesn't follow that relationships are merely instrumental to happiness, achievement, etc. They may instead instantiate or comprise the other goods, in non-fungible fashion, without adding to them.
Update: For a more clear-cut example, note that many philosophers (e.g. average utilitarians, and various non-utilitarians) hold that we may have no reason to bring additional people into existence, but it would be odd to conclude from this that people have merely instrumental value! Deontologists, especially, may simply hold that intrinsic value calls for being 'respected' rather than 'promoted'.
[For more on acquired value, see my post on Cohen-conservatism.]