I agree with your second point, but there's plenty of games like that: Sim City, Any Tycoon game, the economy aspects of RTS (where the fun is obvious), Diner D

I agree with your second point, but there's plenty of games like that: Sim City, Any Tycoon game, the economy aspects of RTS (where the fun is obvious), Diner Dash etc. As the Wii Fit has shown, games are a good way to trick people in to doing work...or exercise :). Oh, and don't make people register.