Ok. Take a needle. Stab yourself with it deep into your elbow hole. It will hurt like hell and it is by no means a crippling wound. Humans generally have a very good sense of their “health bar” because they can feel so many different kinds of pain from so many different organs, but in the game, you have only the visual clue of the screen losing colours. Precise health bar will give you the information allowing you to calculate risks in a fight much more precisely: “I am wounded bu still over the half of my health bar, so this vanguard with claymore still has to hit me twice which is the same as if I were totally healthy”.
Even then with some impairing light conditions (fighting in shadows), you are deprived even of the visual clue. And that’s health, i.e. the more important stat. Leave the health and stamina bars be, they are your best and only friends in the world of chivalry.