Is it really a bad thing if Fallout 3 is "not a Fallout game"?
Just because a game isn't a faithful reproduction of its predecessors doesn't mean it can't be as good as or better than them.
A good example of this is Diablo 3. In it's current state it's a good game, and from the view of someone who didn't play D1 or D2 it seems like a nice next step (although many people who played the previous games would say otherwise). But you have to remember, while a game can, and in some cases should, deviate from it's predecessor it still has expectations and other things it should live up to. Now I've not played Fallout 3 nor 1, nor 2, nor tactics, nor New Vegas (despite owning them all) but if what Wulff says is true, and it's significantly different from it's predecessors then that is a problem because firstly, people who enjoyed the previous games would buy it expecting similar elements to them and secondly it has "standards" (although standards isn't the best word to use here, it's all I can think of) to live up to. So yeah, sequels can be better than their ancestors, but large changes are a problem, that's just how I see it though.