If you thought Bioshock or infinite were simply indictments on Ayn Rand or American Exceptionalism, then you must've also thought Grapes of Wrath was just about a family's migration from the dustbowl to California.
Bioshock frames its story with the ideas of Ayn Rand, but is actually a story about objective goodness, family and love.
Infinite is a story about stories and about the cyclical nature of everything.
I'm not sure Bioshock Infinite was really about one thing. Only about 5% of the game is a story about stories. Most of it is a story about a woman learning to be her own agent rather than a means to other people's ends, and after that it's about the question of self-determination versus fate (this is pretty much the Lutece Twins' entire role). It begins and ends on the note you're talking about here, but those themes don't really seem to be as pervasive as the themes of The Grapes of Wrath.
That's fair. Both games were a bit ephemeral regarding their themes (which were numerous), but it certainly isn't fair to say they're derivative because they "tackled Ayn Rand".
Bioshock frames its story with the ideas of Ayn Rand, but is actually a story about objective goodness, family and love.
Infinite is a story about stories and about the cyclical nature of everything.