The purely mechanistic view is motivated by a mania for objectivity. Of course, that mania is itself relentlessly subjective.
However, the mechanistic view drains all life and consciousness out of the world. There have been objections to this sort of thing from within science. The physicist Ludwig von Bertalanffy, well known as the father of General System Theory, developed his theory as an alternative to reductionist, Cartesian notions of mechanism, which he believed were not only hamstringing science WRT to the investigation of such questions as life and mind, but had deplorable social and ethical side effects for humanity at large. Evidently the Nobel Laureate biologist Jacques Monod detested Bertalanffy for holding such reprehensible views.... (Monod is a great champion of mechanistic reductionism as the prime strategy for biological investigation.)
Such "intramural spats" can be highly instructive and interesting....
Thank you ever so much, dearest sister in Christ, for your excellent essay/post!
Seems to me this mechanistic view plus consequentialism gives us the likes of Peter Singer, bioethicist who believes that parents should be able to terminate their offspring up to a year after birth (or something like that.) The end justifies the means when to them, the whole is the sum of the parts - there's nothing more, nothing precious to be preserved but rather an inconvenience to be eliminated for the greater "good."
Infanticide and euthanasia are just flavors of eugenics, taking out the trash, which sadly can be presented as "politically correct" altruism if one "drains all life and consciousness" out of the world, as you say.