The main thing here is that HP are not just measures of fleshly integrity, but also represent plot armor. John McClane has way more HP than any of the East German terrorists, but it's not because his body is tougher, it's because he has the screenwriter on his side. High HP people are more important, so they get more "chances." A "hit" with a sword can be a sword to sword contact that does no physical damage, but is part of the plot armor being degraded.I guess I see most if not all combat misses" as in fact being outright misses - you either didn't connect with the foe at all or your connection was of so little impact that the foe could - and did - ignore it completely.
Contrast this with being caught in a fireball. There's no way it can miss you entirely, the question is merely how much damage did it cause.
And it only just this minute occured to me after nearly 40 years: the save-for-half mechanic might be no more than a simple way of replicating the idea that not everyone is going to take the same amount of damage from a given effect. More accurate - but also more cumbersome - would be to roll the damage separately for each creature in the area.
Rolling a 2 and being done is, to me, just part of the game.