Ecosystems are the context of speciation. Species are what they are where they are. The comprehensive ecosystem too is a vital survival unity. But when human culture supplants nature, extinction is radically different. Natural extinction is the key to the future because in nature, a species dies when it has become unfit in its habitats, and other species appear in its place.
Artificial extinction closes off the future because it shuts down speciation.
One can say that nature doesn't care about species, and in a way that is true. But it does not follow that there is nothing in nature promoting, conserving, elaborating species, or that we should not care about this. But nature does seem to generate species with remarkable fertility and extravagance in Earth's several billion years of creative struggle. We ought to admire the process as much as the product. Valuing the Rare Rarity per se is not a valuable property.