There’s a lot of serious questions wrapped up in this topic.
In Round River, Aldo Leopold wrote: “The last word in ignorance is the man who says of an animal or plant, “What good is it?” If the land mechanism as a whole is good, then every part is good, whether we understand it or not. If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.”
I don’t mourn the smallpox virus and I wouldn’t be bent out of shape by the demise of Guinea worms (although I seem to recall hearing that animal reservoirs exist for it, making eradication problematic) but the argument that such and such a species is useless/dangerous/cruel/nasty/icky has been at the root of more than one species being wiped off the map. Where does the line get drawn?
Leopold’s Land Ethic speaks to the reality that the natural environment will only be sustainable if humans figure out that we are part of a community of living things that need to be treated ethically both individually and as a community. His earliest work is a century old but even more relevant now than it was then.