It sounds very nice if you don't think about it. If you do, it may occur to you that belief in the vital importance of sustainability is based on an implicit assumption of stasis—a world where, whatever you are doing, you will keep doing it forever. That isn't the world we live in. The critical resource of today may be irrelevant fifty years from now; the pollution of today may be a resource then--consider manure—or the resource pollution. Rabbits were a resource—until they became, in Australia, a plague. Similarly for Kudzu in the U.S.
We don't know how we will doing things fifty or a hundred years hence, but that it will be the same way we are doing them at present is not a likely guess.