Two things:
1. You never "own" a game. Or a movie, song, or even book for that matter. You cannot expect to do what you please with any media. You purchase certain rights of use. If those rights are not broad enough for you, don't purchase. For most, those rights are enough to enjoy the game.
2. Those of you who worry about 10 years in the future might not need to. First, Spore 4 might be out by then (porting all your current creations with every release) and second, that limitation might be eliminated by then. A few years from now they might determine the risk that someone may copy an old game is not worth the overhead of running the over-the-phone verification. Similar things have happened with PC games for me.
"You can never jump away from Conclusions. Getting back is not so easy. That's why we're so terribly crowded here."
Canby - The Phantom Tollbooth
