Just to chime in on all the other stuff, Francisco inherited all his wealth, and spent his life quite literally destroying it (rather than give some of it up to the "looters"). I can't think of a better allegory for crony capitalism.
D'Anconia has agreed with Galt to stop carrying the looters and so he plays the spoiled playboy. Sure, he has a certain duty, but that goes both ways, and if the investors are not adding value then what duty does he have to them other than to do as he pleases? They are trusting that they can make money off of him based on his family history, nothing else. That is, there agreement amounts to: "Go make money as you always have. We would like a share, but you do the work."
I agree with the comments of unalone and guiles. They point out what I don't like about the book, but I didn't see anything wrong with this subplot within the logic of the book.
I daresay I've read Atlas Shrugged more times than you have. Furthermore, though I could be wrong, I would argue that I've memorized more of the central concepts and analyzed them more thoroughly than you have. Judging from how you've written on this thread, you're still operating from a very shallow interpretation of her works, which is antithetical to her own ideas.
The central flaw of Atlas Shrugged is that it denies external possibility. Given her own hypothetical world, it follows impressive logic. However, it ignores the fact that people are not so easily judged. A former girlfriend of mine was an Objectivist and simultaneously an irrationalist. She believed in man as an end unto himself, but also that everything was subjective, there was no absolute truth - and she was a believing Christian on the side. The problem with Ayn Rand's writing is that the two are not necessarily incompatible. You can believe in what she writes and still think that things are subjective, and that truth is difficult to find, and while she would argue that that is a corruption of her ideas, and it is, Atlas Shrugged does not define itself well enough.
Part of the problem is the nature of language, which is subjective. If I tell you that I'm nice, it could mean that I am "kind" or that I am "accurate". If I call my friend a "motherfucker" it means something different to him than it does to Oedipus. Similar, "objectivity" does not have an objective interpretation. Neither does "selfishness". People will never agree over these definitions. Objectivists don't agree over them in their entirety. By that nature, yes, everything is subjective.
But that's beside the point. To give a quick summary of other flaws, I'd say that her writing is preachy, her characters are one-sided, there's no observation of physical stimuli (which is to say, the nature of bad things happening to good people on grounds other than human interference, which leads to questions of philosophy that she neatly ignores), and her book is about three hundred pages too long, drags in the opening, in the latter half of the second part, and John Galt's speech is wholly unnecessary as part of the work. Feel free to respond.