While I agree that Hardcore mode wasn't quite hardcore enough, I don't think you give it enough credit.
- The needs system actually makes food useful.
- Your companions can die, which means you can't just use them as cannon fodder.
- Ammo weight forces you to think more about what to carry and prevents you from being a walking armory like in FO3.
- You don't heal while sleeping, which makes Stimpacks/doctors/etc actually useful.
- Delayed stimpack healing means you have to be more careful in combat.
- Crippling is more significant, given that you can only heal limbs with hydra or doctor's bags.