A lot of the most important parts of a game are lost after you've played it once. Exploration, discovery, challenge, etc. I would almost invariably prefer to play a decent game that I've not touched before, than a good game that I've already beaten three times. I don't think I'm especially unique in that preference, either. People like new content. I'd be very surprised if the average title on the average person's shelf had been beaten more than once or twice.