This has been an interesting idea now that we see this a lot in the new global warming and eco-friendly ads. I can see the "leave the world in a better state" being a personal ambition--and hopefully a collective ambition--but only when I picture myself with children. I guess thats what they're striving to encourage now.
Problem is that most people don't have a reason to leave the world better than it is other than the prolongment of the human race. And naturally, we should be working for the collective good of our species! However, somehwere in evolution we got to the top of the food chain, and with our "intelligence" we don't have much to compete against but ourselves. I think the powerlessness of the UN is a good indication of the limits of the human race in working collectively. Really, this doesn't seem feasible except in alien movies. =X