Meh. Suddenly I don't feel interested in it anymore after you said that. I love the story and setting of rapture. I thought this was a prequel that leads to Bioshock. I guess I was wrong. Oh well.
I agree that its a bit disappointing, I actually expected the same as you. With that said I have no doubts that they will tell yet another fantastic story with an amazing atmoshere. I wonder if the two games will tie together in the end somehow. I'm sure there will be references throughout.