Of course it is useful. The mechanic tells you the mechanical impact (arguably all it has ever told anyone). That being, whether your character can still function (>0 HP) or not (0 HP).
How would you narrate an attack roll that came one point short of hitting the AC?
I’m almost the opposite. If a creature—PC or otherwise—with full 60 hp is hit for 12 damage, narrating that as an actual physical wound/injury takes me out of the fantasy immediately and reminds me of video games (D&D video games included) where every hit draws blood. And you’ll have 6 of those hits, all drawing blood but none of them actually hindering your ability to fight back properly. Just no.
A miss.
Yeah, me too. And thus I wouldn't also narrate a hit as a miss!
Of course, narrating an attack which did hit the AC is also a miss.
Setting aside that the fundamental point of a statistical model is to find out what happens, and imposing our own preferences on the model would result in losing any inherent meaning from the model, we're back to the original point. No, I can't narrate the effect of that hit to involve any degree of physical injury, because that's entirely inconsistent with damage that disappears after a short rest.
Hit points are used for virtually every kind of attack, some of which of course have to make contact for there to be any sense at all. Poison is the obvious example, but what's the point of having fire resistance if the fire never actually hits you? If you're not hit, what difference does it make what kind of damage it was? Yet clearly that does matter mechanically.
Is it a miss if you block it with your shield, or it glances off a pauldon, or you deflect it with your sword?
