Khur said:I do think it is a mere problem of perception, though, for you and Davyn.
That is one way to see it, I suppose ... but I think it's a bit deeper than just perception. I can grasp abstract concepts like hit points representing more than just physical integrity, but other problems come with it. The main of those problems is the fact that the interpretation of a "technical result" depends on events that happen in the future.
For example, let's say an orc damages the fighter for 5 hit points. If this "damage" is later (let's say 3 rounds later) "healed" by a warlord's order, then what really happened is that the fighter dodged out the blow but somehow became less heroic/invulnerable/concentrated or more exhausted or got a decrease in morale because of the orc's attack. But if this "damage" is later "healed" by a Heal check or by divine magic healing, then what really happened is that the orc's blade cut through the fighter's skin and flesh and caused it to bleed.
When my orc rolls a hit and the damage die shows 5, I want to be able to describe what happens right then, and not have to say "Something happens ... but I'm not sure what exactly. I'll be able to say for sure in 3 rounds, when that damage is healed."
That's one of the main problems of the "dual" interpretation of hit points as physical integrity and "something else", which show that it's a bit more than just a question of perception.
Side note. One easy answer to my problem above is to say that all attacks that hit cause physical damage (i.e., the orc really damaged the fighter) and that the warlord's "healing" just inspires the PC to ignore the wound and continue fighting ... but that does not work, since the fighter still goes back to full hit points [= no wound] after the warlord's action.
Another answer is to say that all attacks except killing ones do not harm but simply reduce "combativity" (i.e., the orc missed the fighter and that the fighter just lost some "combativity"), and say that divine healing magic grants inspiration and courage instead of healing physical damage... but then why does a Heal check restore hit points? Shouldn't we use Diplomacy checks instead to cure people?
Second wind and even healing powers have the obvious outcomes in the game of increasing hit point numbers. The question ultimately is: What do hps represent? If they don't just represent physical damage, and they don't, then even a so-called "healing" power might just be strengthening a targeted character's resolve to fight on—or whatever the players and DM decide it means for the narrative at the time.
Yup... but that can only be done at the time of the healing, not when the "damage" is done.
Evidence for this is easily found in that the warlord has the martial power source, which isn't completely nonmagical, but certainly less magical than other power sources.
Now, this is a reverse argument that does not work here in my opinion. The warlord's nonmagical "healing" abilities (as well as the second wind abilities) are the reasons why the "hit points = physical integrity" interpretation does not work anymore; they can't both be used as causes and justifications.
I remember reading somewhere that one of the novel concepts used in the development of 4th edition was that "rules" and "fluff" would interact with each other, while in previous editions, fluff would give birth to rules (and not the other way around). I'll first admit that I am biased here, because I like the "fluff/imagination gives birth to rules" direction, but I do not like the "That's a cool rule, let's come up with some fluff to plug it in the system". I feel that it is what started this whole topic.
I would imagine (but, of course, I can be wrong), that the developpers thought "Clerics that have to spend all their rounds healing are no fun; let's fix that." then concentrated on one solution, which is "Let's make everybody able to heal themselves, and let's make other kinds of healers." From a rule-based point of view, then things like second wind and the warlord's ability make sense ... they allow characters to heal themselves, and open up a new class option for a healer.
But things start to make much less sense (imo) when those "rules" are plugged in the system, because they have to be supported/justified by some fluff. And the fluff that is necessary to bring those new rules in is that hit points are no longer just a measure of physical integrity, that wounds are not only physical wounds, that healing is not only physical healing, and so on.
So, in that sense, I don't feel that you can really use second winds and warlords to justify that the new interpretation of hit points makes sense.

Some people who have posted here have pointed out just such narrative opportunities, such as the yuan-ti seeing he’s got you on the ropes and zealously attacking because of it. And that’s really what they are—narrative, or roleplaying if you prefer, opportunities.
As I wrote above, I could see a yuan-ti "feeling blood" and getting, for example, a flurry of attacks against a bloodied character, or some sort of to-hit/damage bonuses with perhaps a penalty to AC ... but being able to attack everybody around as in a whirldwind attack because ONE of them is bloodied? Why?
I feel like asking ... what "realistic reaction" of the yuan-ti is this rule supposed to mimic? Yuan-tis that fight several opponents and feel that one of them is next to being overcome might start fighting more aggressively against that creature - that, I can buy -; but start suddenly attacking everybody around? I can't see the relation. I guess that could work for some strange/new creatures, but that is not at all why one would expect from a yuan-ti (that being, I'm not a snake specialist, so I might be utterly wrong).
That too feels like a "hey, I thought up a cool rule... can you find some fluff to plug it in?" moment to me.
None of the abstractions of the 4e D&D game are outside the realm of imagination’s ability to explain in a fun way within the narrative of the game. I can’t agree with assertions to the contrary.
You are correct ... it's always possible to find a fun way to explain things. But I feel that sometimes, the only possible explanations are cheesy at best, and that they force me out of the realistic/gritty games I like to play, where combats do cause blood to be shed from wounds that can't just -always- be healed by inspiring words.
That being said, thank you very much for taking the time to answer.