While we hope and plan to defend ourselves against a space rock that
might hit Earth and wipe us out, we often note how the celestial object
that removed the dinosaurs 65 million years ago cleared the way for the
rise of the mammals and eventually us - which is supposed to be a good
thing.

What if space impacts are meant to clean off a species that doesn't
achieve space colonization by a certain point, to pave the way for
another species that can then evolve and do a better job of cosmic
propogation?

Of course there is the idea that Gaia made humans to solve the NEO
impact problem, which it tried with the dinosaurs but after 160 million
years and still no spaceships or nuclear bombs, decided it was time to
try another species.

Just thinking out loud here.