Where, then, does it lie, precisely?
That's sort of a different form of the ultimate question, what is art? Some people say a toilet with a Bible in it is art, others say it's not. Clearly it's doing something for somebody, it's trying to say something, but it doesn't tickle the sense of aesthetic appreciation, so it's hard to accept as art.
Likewise, I don't think you would say that Heart of Darkness, The Jungle, or the film Irréversible were created to entertain. Maybe they do entertain, but the desire to entertain probably wasn't the motivation driving their creation. Like how you might be amused by the Bible in the toilet, but it clearly wasn't done just to amuse you.
The value of The Great Gatsby is (some would say) in how it perfectly expressed the zeitgeist of a time and place. We can appreciate it as a kind of historical artifact, or as an unpleasant journey through a set of unique human failure modes. Most people don't finish it and say, "Wow, I really enjoyed that book."
Anyway, I think we actually agree on this topic in general, I just wanted to answer your specific question.
how it perfectly expressed the zeitgeist of a time and place
I strongly disagree. That kind of mood can be found anytime, anywhere, among any social class.
Guy born with status gets girl born with status who was previously courted with guy born without it who doesn't know the codes of status all that well. The latter sets out to obtain status, at great expense, all for the sake of getting the girl, on whom he fixated as a status symbol and the solution to all his self-esteem issues.
He fails because of his lack of belief in his newly-acquired status, in...
From EY's Facebook page, there were two posts that got me thinking about fiction and how to work it better and make it stronger:
I was wondering if we could apply this process to older fiction, Great Literature that is historically praised, and excellent by its own time's standards, but which, if published by a modern author, would seem substandard or inappropriate in one way or another.
Given our community's propensity for challenging sacred cows, and the unique tool-set available to us, I am sure we could take some great works of the past and turn them into awesome works of the present.
Of course, it doesn't have to be a laboratory where we rewrite the whole damn things. Just proprely-grounded suggestions on how to improve this or that work would be great.
P.S. This post is itself a work in progress, and will update and improve as comments come. It's been a long time since I've last posted on LW, so advice is quite welcome. Our work is never over.
EDIT: Well, I like that this thread has turned out so lively, but I've got finals to prepare for and I can't afford to keep participating in the discussion to my satisfaction. I'll be back in July, and apologize in advance for being such a poor OP. That said, cheers!