The issue is that we're talking about science fiction here. Note that while the genre in theory is not so young (just to give one example, Icarus could be considered science fiction, as it featured technology that made something possible that actually wasn't in that time). The concept of actually visiting different planets is (200 years is young in this context).

Also, stories are essentially memes. I would argue there isn't a single truly 100% original story. Everything is ultimately tailored together (while still allowing for creativity and innovation) from ideas that the writer(s) picked up from other writers. Like the evolution of genes, the evolution of memes takes time (while it is faster by orders of magnitude).

If you can't go to other planets you're stuck on earth. A scenery of a location is a functional element of a story if it's of any importance. For instance, if you tell the story of Columbus, an important element of that story might be the rough sea. That's a fixed location, as a plot element. Similarly there are stories that involve traversing a desert. Again, you're immobile because the roots of the memes that we keep evolving lie in a time, where you couldn't change location that fast.

Now, if you write a story that involves planets, they're locations, and since the story is inspired by previous memes it makes sense that that location has fixed properties, such as being extremely cold.

So of course you can introduce a planet with realistic heterogeneous climates, but in order for it to be actually part of the story, you have to come up with a story that genuinely involves these features, and you have little inspiration to work with.