Good call about the Big Daddies. They really got a raw deal, and it immediately struck me during my first encounter with one that "wow, this is the only person in this place that hasnt been hostile to me so far."
I've heard people say that Rapture failed because Ryan wasn't really loyal to its ideals, and behaved in a hypocritical fashion. But Fontaine seems to me to be a perfect end result of the Objectivist values of the city, and he lived up to it. Even if Ryan hadn't gone to war with him, I think Fontaine's greed and indifference would still have driven him to destroy Rapture. He would still have used it as a testing ground, and he still would have tried to bury the evidence. So I am in agreement with you that the Objectivist values--at least taken to such extremes--were indeed to blame. And in that sense, I do feel the blame spreads to the populace, who bought into those values to their own detriment. I just hope that some of the survivors would learn from their mistakes.