Hit points representing "fatigue" or "luck" sounds nice in theory, but that doesn't reflect the reality of the game. Otherwise, why do they recover so slowly? Should it really take days to rest to recover one's ability to dodge blows? That's neither realistic nor cinematic. Likewise, why are healing magics the primary means of recovery? And look at monsters in the MM: monsters with higher HP are "tougher"; faster, more nimble or harder-to-hit creatures are given higher ACs instead.
In effect, hit points represent physical toughness in D&D. Hit points try to serve "double duty" in D&D as both physical hardiness and luck/dodge ability -- and they do not do this well.
Star Wars and D20 Modern take slightly different approaches to fix this problem ...