Correct me if I'm wrong, but as I recall it has always been the case in DnD, at least since 2nd ed... except for 4e that introduced the Bloodied mechanic but even then, it didn't really affect combat effectiveness, more like gives a bonus once in a while depending on powers and races, or trigger some special actions from monsters.
A good system that deal with that is Trudvang Chronicles. In this system, the Body Points are clearly only physical damage and the more damage you get, the less effective you'll be (-1 once you lose a quarter of your BP, -3 when you're at half BP and -7 once you lose three quarters... then you're dead). Also, you never really get more BP as you gain experience, what you start with is what you get for your entire adventure life until you die a horrible death... to counter that cruelty, you can try to parry each attack that hit you, but you need to keep points available for that and it's no guarantee. Also, weapons and armors also have body point and can potentially break if you're not careful. If I want to play a more simulationist gritty survival game, that's my system of choice. But if you want my opinion, while it is nice to try to simulate real life and getting hurt, what I feel like it does is just slow down combats, since the longer you fight and get hurt, the less effective you get so it becomes harder and harder to hit the enemy, and the same things happen for the enemies that have more and more trouble hitting you... so honestly, I think I prefer the full combat effectiveness of DnD over the more real cruel rules of Trudvang... still a wonderful game!