Because it matters.
Commending David Tyler for a recent article on the subject:
Extensive studies of fossil skeletons of Australopithecus sediba provide fascinating details of the anatomy of this hominin species, but do not convincingly indicate its position on the evolutionary route to modern humans.
One should ask first, why is human ancestry important? Who cares much about cats’ ancestry?
Cats might be really annoyed (if they were capable) that they may share an ancestor with, like, bow wow wow. But so?
The whole point is that they are not capable of caring. When will we finally start studying intelligence seriously? Recognizing its capabilities and limits?
Human ancestry only matters because we are not really just animals.
Something is wrong with a society that does not just recognize this fact.
Why do the people who say we are destroying the planet also proclaim (almost always) that we are just animals?
See also: The fall of Australopithecus sediba