Apologies if I'm reading this wrong, but between this question, and casually comparing a possible origin of life on Earth to a venereal disease, it just all strikes me as very misanthropic.
My answer would be -- it's important if we deem it important, whether that's rational or not. If we start from the premise that life is good, that humans in particular are the most interesting thing out there as far as we can see, then it isn't totally bizarre that we should wish for the show to continue, extend it as far as we can. In that view, being bound to the fate of our home planet seems like an arbitrary restriction.