There's a lot of lipstick application to the proverbial pig going on in this thread, IMO. A surfeit of mechanics for D&D which are unenvisionable or difficult to map to anything going on in the fantasy world are IMO just plain old bad game design, not narrativist, dramatist, cinematic, or any kind of self-important sounding game design theory jargon word. But again this obvious flaw gets the runaround.
That's because it
isn't "bad game design" or "an obvious flaw" to some people. I offer the following as an example of the difference between "It is bad" and "I think it is bad". Note the careful use of the phrase "This approach doesn't work for me", indicating that the views expressed are an opinion, and not objective truth.
There are a number of ways in which you could approach the issue of hit points.
First, you could take the approach that hit points are entirely "meat", and that a 4 hit point wound means exactly the same thing for a normal man with 4 hit points and a 6th-level fighter with 40 hit points. This approach doesn't work for me because this means that a 6th-level fighter could be sporting up to nine wounds that would have killed a normal man (sword thrust to the gut, arrow through the neck, broken skull, etc.) and would (1) still be making attack rolls normally; and (2) eventually be able to recover through non-magical means.
Second, you could take the approach that hit points are partly "meat", and partly some other factor, such as the ability to dodge attacks and turn otherwise fatal injuries into less serious ones (for the sake of this argument, let's call this other factor "vigor"). I see this approach as an improvement over the "entirely meat" approach because when a 6th-level fighter takes a 4 hit point wound, as long as it doesn't reduce his hit points to 0 or less, he isn't actually stabbed in the gut. Instead, he is able to avoid the full effect of the attack at the last second, so that a sword thrust that would have stabbed a normal man in the gut is reduced to a grazed stomach or something along those lines. The 6th-level fighter has still lost 4 hit points, but the physical effect of the loss of those 4 hit points is different from the physical effect that it would have had on a normal man.
Now, the approach that hit points are only partly "meat" could be further subdivided into whether, when hit points are lost and regained, they are always lost and regained in exactly the same proportions of "meat" and "vigor", or whether "meat" and "vigor" points can be regained separately.
The approach that "meat" points and "vigor" points are always lost and regained in the same proportions does not work for me, not because of the hit point rules, but because of the healing rules. If a normal man with 4 hit points can recover from a 3 hit point wound with 3 days of natural healing, it seems to me that a 6th-level fighter with 40 hit points with 30 hit points of wounds should be injured to a similar extent and should also be able to recover completely in 3 days. Unfortunately, this has not been the case in most editions to date. Interestingly enough, if hit point recovery were made proportional to full maximum hit points (something which was done in 4e), it would have made this approach more acceptable to me.
Given that I already have a preference for hit point approaches where hit points represent both "meat" and "vigor", and a preference for approaches in which "meat" and "vigor" points can be gained and lost separately, it is not too far a step from that to an approach where "vigor" points can be regained far more quickly than "meat" points.
That's all there is to it, and I certainly would not presume to suggest that a preference for any other approach is "bad game design" or "an obvious flaw".