Agreed on the “shifting focus” part for vignetting specifically - but everything else… outside of specifically tailoring to fit a particular “aesthetic” I think are crutches that are generally used to obscure an overall graphical presentation in order to work in a similar way to how squinting your eyes works.
I agree that highly stylized games like “Bodycam…”
…use it to create a highly appealing visual aesthetic designed to match an actual low-fidelity police body camera, but Battlefield and CoD have much less excuse in my book.
The camera aesthetic stuff only makes sense on things like the AC-130 killstreak in CoD where you’re emulating the on-aircraft cameras actually used in the real deal.