May be it was supposed to be like that, hmm? Just wait until you get to the Ringed City DLC or Anor Londo. But even without it, the intro tells a story of converged lands...
Anyway, I must say I had similar feeling up until about 1/3 of the game. And then I found a lot of new memorable locations (and also the game appeared MUCH bigger than I had previously thought), so in the end it didn't feel like the installment was based on recycled design at all.