Undrave
Legend
Moreover, if we do pretend that it's reasonable to assume any PC of a given level will deal at least 8 damage with an attack, then why not model those minions as having 8hp? It would solve almost every complaint, while being virtually identical in play (according to your argument). The only possible explanation I can see is that they were intentionally trying to alienate any potential player who wanted to take the game seriously; in which case, mission accomplished.
No, it's just so you DON'T have to track their individual HP. That's all. I'm pretty sure Minions don't take dmg on a miss either. For minions, 1 HP doesn't actually mean 1 HP, it just mean "beat their AC (or other defences) once to get rid of them". You don't roll for damage and you ignore anything but immunity.