I think the two ends of the SF spectrum are: Type-I, where the author tries to come up with "big ideas" as described in the OP and their ramifications wherein t

I think the two ends of the SF spectrum are: Type-I, where the author tries to come up with "big ideas" as described in the OP and their ramifications wherein the idea is the important part, e.g. Snow Crash; and Type-II, where the the SF part is just an artifice to expose and explore aspects of humanity or some deep philosophical issue, e.g. Solaris, The Handmaid's Tale or the stories of James Tiptree Jr. (you've got to read "Houston, Houston Do You Read"). Works of the second type don't really need to push big ideas or ideologies. In fact, for most of these, the SF element is something that will be quickly introduced and got over with to come to meat of the story, similar to how better folk tales and fables work: "Let's just assume that animals can talk, now one day ...", or "Aliens have invented a pheromone/toxin that turns sexual urges in males into uncontrollable physical aggression, this is what happens to humanity".