It seems to me that language choice is part of characterisation, and whether or not it works for the story depends on whether it is correct characterisation for the POV character. So yes, what you’re saying, I think you’re right.
I always say everything is part of characterisation, but I’m really serious about this.
It’s easy to see how description is character. Everything you describe, in first or tight third, is seen through the POV’s POV. If they see a flower, you’re doing it wrong, one person sees a rose going to seed that should have been pruned days ago, another sees a rose that is a poignant reminder of what might have been, another thinks that rose would look just wonderful pinned to a lapel just a little broader than this one, another sees a plant so peculiar that it has a cluster of petals spread out evenly around its stamen, and so lightly balanced on the branch that it sways at even slight atmospheric motion, while fifteen others walk straight through the garden and in at the door. And I haven’t said anything about the colour of the roses…
The word choices, the rhythm of the words, the use of technical words, the use of Latinate vs Germanic words, the use of metaphor and simile, all of it is characterisation, and needs to work as that if it’s going to work at all.
If it works as characterisation, it works as prose. If you look at something like Rushdie’s Midnight’s Children, which is one of the lushest books in the world, it’s just as “grabby” as something really stark, because the prose belongs with everything else.
Diamond Age (which had been mentioned elsewhere in the thread) is in omni, incidentally, though I think our division of things into first (there are at least three firsts) and third (third is a very weird POV and I think there are at least four that I know of) and omni (at least three, and it’s possible to see omni as a special case of first) isn’t actually as helpful as it might be.
Expanding that last bit:
Most of the literary terms we use come from literary criticism, and they’re very useful when you’re looking at a written text, but not so much so when you’re writing one yourself.
The normal division of POV into first, third, and omni, leaves a lot out.
There’s first reflective, like Renault’s The Persian Boy and my The King’s Peace where you have a “memoir” context in which the first person voice is telling a story after the fact for a specific reason. Brust’s Vlad books are a very interesting case of this, because when and who Vlad’s telling the stories to becomes actually plot-relevant in later books. Also, Brust specifically addresses the issue that first person narrators lie. Even when they don’t lie on purpose, they’re inherently unreliable by definition, even when they’re not intended as unreliable narrator per se. They’ll see things from their own angle. They have their own sympathies. Disadvantages are the limitation of the POV, you can show one character brilliantly, but you can never show other characters directly, they’re all filtered.
These last things also affect the POV I call first headlong — best example is Dodie Smith’s I Capture the Castle, written in diaries as the plot goes along. First headlong has a peculiar charm. It’s used a lot in YA. I used it for the alternating first POV in Farthing.
Then there’s first present — best example Piercy’s Braided Lives and lots of short fiction. First person, present tense, no reflection, no knowledge of what will happen, no shaping of story by the narrator. I tend to find this a very immediate way of writing because there’s no selection filter. It’s great for up-front description of moment-by-moment events. I strongly recommend it as an exercise. If reflective is a memoir and headlong is a diary, present is a core brain-dump. My unpublished novel The Rebirth of Pan is written with alternating chapters in multiple first presents.
With omni, there are three main forms still in use. One is the Dickensian “bestseller omni” which is like a case of third person with no POV discipline. Everyone gets their two paragraphs of POV. It’s popular, easy to tell stories with, because hey, you can give everyone’s POV. Examples would be the kind of bestseller you pick up in airports, and Dickens.
Then there’s the Trollope omni, also seen in Jane Austen, where you have a narrator directly addressing the reader. This is actually a special case of first. While your omniscient narrator knows all and tells all, that’s all through their filter. In omni, like first reflective, you can stop and address the reader. (I wouldn’t recommend doing it too much, but it’s a delicious temptation.) This is what I used for Tooth and Claw. The main problem is distancing and causing the reader not to care. In my experience, distance is weird in omni, because the more you close up the further you get away, it’s better to let things stand for themselves. Trollope omni’s always going to be a little distanced. You’re not going to feel the bones crack between your own teeth. But that’s OK.
Thirdly, there’s fairy-tale omni, the “once upon a time” style used to tell fairy tales. There’s a narrator, there, and it’s a whole mode. This is what I used for my short story On the Wall and a ton of unpublished fairy tale retellings and the alternating chapters of The Rebirth of Pan.
Then there’s third, which is actually a whole bunch of stuff and very weird when you think about it, but because it’s been so popular in the last century it has got to look normal to us. I wrote The Prize in the Game in four alternating tight thirds, and also the alternating chapters of Farthing. All the same, I don’t feel I have a handle on it the way I do on the various firsts and omnis. Third isn’t a traditional way of telling a story. It isn’t “No shit, there I was” and it isn’t ‘Once upon a time” and it isn’t “It was the best of times, it was the worst of times”, it’s something like first present, but without being either first or present, and it’s conspiring with the reader to not exist, to not have any notice taken of it, as if the prose were invisible, and yet shaped, always shaped, by the underlying characters. Third doesn’t necessarily put you in someone’s head. it’s very different from first with the pronouns changed. Third is just plain weird, and I’m not going to try to categorise it here.