I'm not quite sure you understand what hit points really represent. They're not simply 'health'; they're a character's ability to take hits and damage and still be healthy enough to function. High level fighters are better able to roll with a punch, so to speak, than a low level one, as they have more experience dealing with that sort of thing.
Personally, I don't think there's anything inherently wrong with hit points. They're simple to use and understand. If they're positive, you're good. If not, you're not so good. However, I do feel the way they are distributed in D&D could be adjusted a bit. For instance, 1st level characters should probably start with something like 10 + their current hit die, but gain only half, a third, or maybe even less of what they gain now per level. Skills and feats could be used to help absorb additional damage, if desired by the player.
Besides, a highly realistic damage system is not without its pitfalls. Low level characters are more likely to sustain serious maiming. At the same, they also don't have the resources to recover from them, like spells, items, and gold. This will also likely increase the amount of saving and reloading the player is going to perform, as they will save often in order to prevent their characters from receiving serious harm in battle. Finally, this would seem to seriously complicate things (not necessarily in a good way) the combat oriented characters, without having any affect on other character archetypes.
