Preservation of life is a worthwhile aim. Only one planet is known, by us, to carry life. Keeping all of your eggs in one basket can be a bad idea. There may be places in the universe that could support life, but currently don't. Destruction of other species is generally bad.
Life can exist without people.
I accept that others will not accept all of the above, for a variety of reasons. Anyway, starting with these assumptions, it may be argued that it would be worthwhile to spread examples of Earth derived life to other parts of the universe, whether people accompanied it or not. The active intentional spreading of life to other parts of the Universe is generally referred to as directed panspermia. We definitely don't know enough at the moment to indulge in directed panspermia without risking such destruction. The presence of liquid water for at least some of the time would probably be a minimum.