I agree with you fundamentally that there is no inherent value to the species we have (actually, I don't believe that is an inherent value to
anything, but I digress), but, the value of the selection of species we have
to us as humans can be calculated in terms of what they provide us as people.
Overfishing, for example, means eating sushi will likely become a thing of the past at some point, and will result massive economic losses for industries based around it, from fishing to restaurants. And, many people enjoy seeing animals in their native habitat in addition to, or rather than, in zoos. They enjoy birding, or seeing animals when they are out camping and such.
And, most importantly, while you are correct that extinction is, and always has been, happening, the
rate of extinction has gone up dramatically since the Agricultural Revolution. That has caused problems for humans.
The Nazca civilization collapsed after they made virtually extinct a particular species of tree in order to make room for cropland, not realizing, or not sufficiently appreciating, that that tree created and preserved the water table that the population depended on for irrigation and drinking, and also prevented the soil erosion that ironically ultimately caused massive crop failure. So, my primary worry is that when you pluck one species that seems relatively unimportant from an ecosystem, it turns out to be a lynchpin that holds together the means for humans to survive.
Colony collapse disorder is scary as shit to me for this reason.