I mean, I feel like it does give one answer why, but you're dismissing it out of hand much like all the other answers you've gotten in this thread. It seems you simply don't want to directly engage with the subtext of monsters (and themes as discussed above). That's fine and valid, but demanding other people justify their enjoyment of it while refusing to show them or their answers any respect is a good way to drive off conversation.
I Don't Know How Else To Tell You That Some People Like Telling Stories
fuck dnd for a minute cause i wouldn't play it if you paid me, and even forget the fact that as the most popular rpg there are so so so many people who want and would benefit from having more storytelling tools to tell the stories they want to tell in the system they want to use. fuck all that for a minute.
you're coming in here picking fights on every post in the "narrative tools" thread about how Narrative Tools Are Bad and youre So Angry That People Want Them. you're repeatedly dismissing people's legitimate opinions that, in a genre that is largely about telling stories, that people wanting tools to make games where the story isn't 'i found the cleverest way to solve this tactics/thought puzzle isn't my character cool' or 'let's get loot and kill goblins' or whatever, is a bad thing. i'm sorry you've declared some huge crusade against "story gamers" and i'm sorry that there aren't enough angry grognards here for your tastes but maybe let those of us interested in telling stories, talk about how to do that better, without jumping in on every post to say that it makes you so mad that people want to tell stories? maybe take a step back, my guy, and realize that maybe this conversation wasn't for you to begin with, and was for people interested in narrative tools and the construction of a hypothetical platonic session, like the OP said. if you want a groggy thread to rant against people telling stories, go do it somewhere else; picking haughty "debate me coward" fights repeatedly about "explain to me with logic why you like telling stories" over and over is clearly not productive, right now! take a walk, some deep breaths, and then if you wanna come back and treat people with respect and listen to them instead of fighting some strawman proxy fight please come back and hang out!
you're still picking fights about people daring to want to play games different from you but go off i guess
My understanding of your line of thinking, Axes&Orcs, is that you're presenting two points:
1. D&D is not (and is not intended to be) a game that's designed with narrative structure in mind. (And maybe 1a: If people want narrative structure there are better games out there.)
2. Because 1, creating space in the text of D&D for what we might call "narrative training tools" is unnecessary.
If those are accurate readings of your points, I agree with point 1 but I think point 2 is no hill to die on.
You're right that D&D was designed with particular goals in mind, a lot of people use D&D for stuff that's well beyond those goals (my feathers always get a bit ruffled when I hear "we played the best game of D&D ever last night... we never even picked up the dice!"), and those people might have an experience that's closer to their flavor of fun if they used a different game.
But for point 2, I feel like there's a lot of stuff in the D&D books that people never use (if we limit ourselves just to the PHB: travel, encumbrance, trade goods, underwater combat, etc.). To me, it doesn't feel like a betrayal of D&D's design if WOTC adds a few paragraphs (or even a whole chapter) on how narrative structure can be noticed and highlighted in the course of improvisational and/or tactical play.
Fundamentally, the reason we play games instead of rolling dice and doing math with the results is because games are emotionally stimulating. That is, ttrpgs produce emotional responses (whether the emotion in question is fun, fear, sadness, etc.) and we play primarily for these responses. The challenge of working out how to get the enemy's hit points to 0 is, in contrast, intellectually stimulating; the part where you're an elf and the enemy is a dragon is the part that makes it fun or scary rather than simply challenging or interesting. Without the narrative, the game becomes "component one performs operation thirty-seven, decreasing component two's attribute eleven from one-hundred and sixty-two points to eighty-four points." So, the narrative provokes the key emotional response that makes the game worth playing. Metaphor, as you probably know, is the among the most important tools that narrative has for provoking emotional responses (possibly the most important, discounting base sentimentality). A game that ignores basic understandings of metaphor (or a DM who doesn't understand the metaphorical frameworks they're working in) produces narratives that are dissatisfying on a subconscious level. This isn't the worst thing in the world, and I honestly think that D&D's flavor text does a fantastic job of implying its metaphorical framework for players and DMs. But having an understanding of the essential narrative at the core of a game you're designing and the metaphorical framework you're working in lets you design your game so that your players are incapable of missing the particular emotional response you intend to provoke, and that's the idea at the center of this thread.
Very late to the party here, and I think from the deleted posts you've dis-engaged, but real quick, as to why D&D would benefit from narrative tools, well, it's because approaching fiction as a story comes natural to us as humans. People embellish anecdotes and give them a plot because a simple recitation of events can be pretty boring, unless those events are pretty damn amazing, and even then, it's better with a plot.
So, it's very natural to think that as the gateway to the hobby for many, it might be better to talk to people in the sort of language they're used to from other media, rather than in the simulationist wargaming language that is its default. You may disagree, but wargaming, like hardcore strategic boardgaming, is an acquired taste, and while it's a taste I like, among many, it's going to be confusing to someone who isn't already steeped in its culture or isn't coming from a wargaming or tactical / strategic gaming background. (My personal problem is that D&D is a terrible wargame, and I like more narrative games just as much so I'd rather play those than D&D, but that's another, uh, story.)
Of course, the one attempt to make use of the lessons learned from a medium that was heavily influenced by D&D, video games, resulted in 4e, which became one of the more reviled editions, even though that arguably was the best modern language for thoughts like "this monster doesn't have any context other than it being a cool monster to fight." (Personally, I felt like 4e came a lot closer in spirit to the way things were done "back in the day" while accepting modern innovations, but it appears if you can't kill a 1st level PC with a simple orc stab, it's not D&D or something. But again, my personal preferences are another story.)
There's a strong element of wanting to eat one's cake and have it still sitting untouched on the plate in some elements of D&D fandom, where fans want to claim D&D is good for deep story but don't want to engage with any tools that make it easier to do that, and still want it to be a tactical wargame, without engaging with any of the innovations in that realm since the 1970s. And that's on top of the whole "adventurers as colonizers" problem.
I don't think you need a BA in Art, Media, and Culture to understand that. Mine was a double major in Computer Science and English, by the way, in case it matters. ;-P