The problem with creating something new from a business perspective is that its a risk. There isn't an established fan base and characters with which to work with and companies stand to lose a lot of sales.
I like sequels.When your thirst for more than the original is unquenched, its nice to delve into a familiar game with new features. Fable 2 takes place 500 years after the original and will more or less be a different game than Fable 1, only sharing setting and game mechanics in common(even those have been changed up a bit). Guns,dog companions, extended online play in addition to other stuff have been introduced.Can't see why anyone who completed the first game satisfactorily would dismiss the second installment of Fable under the assumption that its only a sequel.