NintendoWiiFanboy has an interesting article about Nintendo (and every game development company, for that matter) re-using game assets. Artwork, concepts, even entire game engines are recycled to provide the framework for many games. The pros, as Fanboy suggests, are obvious: "reduced cost, quicker development cycles, and less need for debugging", and the only real drawback is that people like us notice and are quietly disappointed.

At the end of the day, does it really bother us to see recycled game parts in "new" titles? In my opinion, whatever helps Nintendo keep costs down and focus on creativity. As long as it feels new, it's new to me.