My use and play of D&D I think matches up (or more to the point has influenced) how I play video games and what I enjoy best about video games (not only the ones I play but how I experience them.) So the MDA is interesting because I've been thinking about my answers from a video game perspective and realizing they directly apply to my roleplaying and board game playing as well.
For me, the first is Fellowship. And it's not just playing games with other people... but more importantly playing games with people I know and like. Playing with my friends. Forming my community within the game playing. And this is actually an important distinction-- I would rather play a group game (like an MMO) solo, if I can't play with my friends. When I play WoW... it pretty much is a solo game to me because playing with other people I don't know for all intents and purposes to me is like playing with AIs. If I'm on Board Game Arena and playing whatever board game I've pulled up and hit the 'find me a game' button... I will play the board game with the random people across the globe it connects me to... but I don't necessarily enjoy it (moreso than if I was playing against computer bots I mean.) This is also why I have never really gotten into playing D&D or other RPGs on places like Fantasy Grounds or Roll20 with just random people I connect to-- because for me it's not about playing with just "other human beings"... it's about the personal, face-to-face, relatable connection I have and get with the people I care about when I sit at a table with them.
That has always been my most important reason for gaming-- the fellowship and comraderie of doing something with my family or friends.
Secondly it's Narrative. I love interactive stories. Stories that I can be a part of. I will always lean in those directions when it comes to the games I play, video and roleplaying especially. I need the story to become engaged with the product or connect to the mechanics. First-person shooters in and of themselves do little for me and I don't tend to play them when it's just shooting for shooting's sake. I usually need an engaging reason to compel me to use a little stick to move a cursor on a screen in front of me and then press a button like some sort of pavlovian dog. Give me a narrative as to why I'm moving the little stick around to move the cursor around to place it at a point for me to then press a button and I will be so much more compelled and interested in doing so. It's the same thing like in tabletop games-- I don't usually play many card games using normal decks of cards, but will play and enjoy card games like Fluxx, Love Letter, or Magic... because the games have at least a small amount of story to make the actions aesthetically pleasing. Uno is fine... but Exploding Kittens takes the mechanics of Uno and then places a thing layer of story on top of them-- collecting cats, attacking other players with cats, stopping other from attacking you, and then blowing other players up with cats. It ain't much and it's barely what you would call "story" (and I know some people would say it's not even actually "story")... but at least to me that layer makes the mechanics more compelling for me to play than just purely "Here are numbers and colors, play cards moving around the table." And if I get so into the narrative weeds over video and board games... then I don't even need to explain anything about it regarding RPGs-- the narrative and story is pretty much the entire point.
Then my third one I chose was Fantasy... which to me I took as taking the Narrative as given to me and then actually engaging with it by pretending to be a part of it. I'm an actor and improvisor... my whole life has been pretending to be things I'm not. And I love doing it. Which is why I love playing RPGs, because then are an extension not only of my hobbies, but of what I did as a kid. I played with G.I. Joes with my friends and we'd make up all kinds of stories and events using the Joes. Or my WWE wrestling figures, or my Hot Wheels on my friend's train track city table set-up. It wasn't enough to just push those little cards around... it was becoming a character within that car, and then the actions and stories that character did as I pushed the car around the cityscape. RPGs are no different... especially when I use miniatures and have grid maps-- it's like playing with my G. I. Joes all over again (just with game rules dictating some of my actions.) But it's the sublimation of myself into the world we are all playing in that is important to me... and reacting truthfully and honestly to what is happening within the world-- engaging with the fantasy-- that takes front and center. And which is why I will always, always, always throw away the game mechanics whenever they get in the way of engaging with the fantasy logically, emotionally, and truthfully. To me, the honesty of the story and our place within the fantasy we are all playing means so much more than "getting the game rules right". Frak the game rules! They have their place... they are what makes these games actual games... but mechanics that forsake story are disengaging me from the Fantasy I have placed myself within. And I will never do that.
You can strip all the story off of the game mechanics of "D&D combat" and play the game with no more in-depth aesthetics as Uno. Just a bunch of numbers you add and subtract from each other-- randomized via dice or not-- until you reach some "victory condition" like a certain number reaching 0. Which is fine I guess... but I personally do not tend to enjoy games like that. If there's no Fantasy to submerge myself into, and no Narrative to engage with... I just don't have any compelling reason to play it.
But I'll improvise stories with my friends all day long.