Last night I was reading Samuel Delany's book About Writing, and I came across this provocative sentence: "In one way or another, directly or indirectly, most good fiction is about money."
Delany was not talking specifically about SF. In mainstream, he makes a pretty good case. He says that much good fiction is about a character from one socioeconomic stratum entering another, or about the clash of social classes divided by money, or about people who gain a lot of money, or lose a lot of money, or need a lot of money, or are disinclined to associate with the differently monied. Those cases cover Les Miserables, Gone With the Wind, all of Jane Austen, The Great Gatsby, Vanity Fair, most of Dickens, An American Tragedy, Revolutionary Road, all of Colette, The Grapes of Wrath, Of Human Bondage, Howard's End -- to name just the first, diverse batch of books to come to my mind.
In SF, the situation gets murkier. Certainly books like Heinlein's The Man Who Sold the Moon center on money, and so does LeGuin's The Dispossessed, in that she is trying to work out a society that does not use money (making its absence one of the foci of the novel). Robinson's Red Mars yes; Gibson's Neuromancer -- yes; my own Beggars in Spain -- yes. But "most" good SF? Although money can translate into power, and much SF is concerned with power. Money can also be security, opportunity, freedom, or luxury -- all SF concerns.
I think Delany may be correct. He says that books that don't have money as at least one of their main concerns, feel "thin." And that needs very, very careful thought.