Plus, at a certain point we should probably ask what we're even doing here. At the same time and using the same ostensible "pro-environment" framework, we:
1. refuse to engage in biome modification to save soon-to-be-homeless species like the Axolotl,
2. are willing to go to great lengths to preserve existing biomes exactly as they are, such as opening up owl hunting permits to protect the western US's shittier owls from encroachment by the dominant eastern species, and
3. are trying to revive mammoths and dire wolves to increase biodiversity.
If we truly care about biodiversity, we should probably decide upfront why we aren't protecting some of the 400K species of beetles or 150K species of flies (together making up ~1/3rd of all animal species) instead.
Personally, my preferred answer is simpler: embrace human aesthetic preferences, rather than pretend we're doing all this for some altruistic, scientifically-supported cause. Not only should we respect nature, we should respect its inherent capacity for change and disregard for human morality. Nature is ambivalent towards mass extinctions, much less specific ones!
TBH, the Red Mars books' discussion around when and why to preserve abiotic martian landscapes may have radicalized me on this issue...