How important is "realism"?

[Garthanos]

I'm all for realism when:

• There is someone at the table who actually knows how it is in real life, and not just "it's common knowledge!"

common knowledge : being wounded is massively impairing, heroes only persevere.
medical science : Everyone's body actually responds even to many very severe injuries with adrenaline and natural pain killers to temporarily prevent most impairment, till after the danger seems over. (Psychology) Someone feeling somebody else is there they can trust to handle the danger may trigger the impairment. And even minor seeming injuries can be deadly eventually.
martial science (military studies): people rarely loose more than 5 percent efficiency before being fully impaired. (Different military studies) Some of even stereotypical tough guys (Spec Ops) go down to what seem minor injuries when they had survived more "major" ones before (it is highly erratic)

Spoiler: caveats

Reading studies is not research and if you lack the science to interpret them or even know how to reject them (sample sizes and correlational P factors etc.) it's not even useful. Some of the above I read so long ago I cannot attest to the accuracy of my interpretation nor my memory of it. I do not know how the military studies measured impairment they did not provide much details as I only read a synopsis (which may have been influenced by ahem bias), so grain of salt, its as "realistic" as I can conjure.

• The system we use doesn't oppose it and there's no need for a mechanical change

Minor changes I am up for actually...but accurate wounding might be closer to some saving throw variant similar to that in mutants and master minds but with extra after the battle shock checks for unconsciousness, death and details like afflictions. (medieval environments gangrene and other fun too)

See below for genre divergence ahoy.

• It still lies within genre conventions

this however is vital.

If any one of these doesn't apply, hard pass.