Okay, seriously guys, you are complaining of shoehorning plot into Bioshock 2... wherein the original had a villain whose best plan of action was the most RIDICULOUS series of events ever conceived for a video game outside of a Metal Gear game or whatever Capcom's next attempt to explain away the RE plot will be.
The plot of Bioshock was dreadful.
The setting, the backstory, the storytelling, all of that was top notch. SO top notch apparently that you are all missing how profoundly, completely illogical, patently absurd, and totally ridiculous the villain's plan was.
Which, I guess, in a roundabout way, makes it something special.
But the plot ain't exactly some sort of pristine egg, that should you even touch it will shatter it. There will be a sequel and it will probably turn out pretty damn good.