Plots are not that different from each other and there's little originality in them...

There is nothing new under the sun.
Fortunately, you are not playing with the sun, you are playing with friends, and between the lot of you there's new plots, characters, and settings aplenty.

>postmodernism

There isn't many plots that cannot be reduced to 'find the mcguffin' or 'defeat the bad guys' though. The more you play the more samey the plots start to feel.

>No. Characters and setting are inherently more flexible than plots.
Disagree. The number of possible characters is limited, while a plot can be anything.

I'd say that while it's true that the trappings of a plot can be anything, they can still be reduced to one of the seven Jungian archetypes making them feel not unique.

What aesthetic means in this context? As in, what makes an ending aesthetic or not?

Disagree with the first half. The "all plots are unoriginal" opinion really only applies if you strip stories down to the bone, eliminating all considerations of what actually happens. If you're the kind of person who does that, you probably also think TVTropes is a useful writing resource.

In western fairy tales, Kawai notes, stories often resolve with a conquest, or with a wedding. Examples are numerous: Sleeping Beauty, Cinderella, Snow White, etc. But in Japanese fairy tales, there is rarely this kind of union. Frequently, stories resolve with “an aesthetic solution.” And by aesthetic specifically means images from nature. See “The Bush Warbler.”

"A woodcutter is out in the woods, when he comes across a mansion he has never seen before. He encounters a beautiful woman, who invites him into her house and asks him to look after the property while she is out—if he promises not to look in any of the interior rooms. As soon as the woman leaves, the woodcutter breaks his promise. He wanders around and finds three beautiful women sweeping. They see him, and glide away “like birds.” Alone again, the woodcutter begins to steal intricate, gilded objects. At one point, he picks up a nest with three eggs. He drops the nest and the eggs break. The beautiful woman returns to the house and chastises the woodcutter for “killing her three daughters.” She transforms into a warbler, and flies away. When the woodcutter comes to, he finds himself completely alone in the woods, with none of the pilfered objects in his possession and with only a memory of beauty."

This kind of ending is not uncommon in Japan. In a western fairy tale, the woodcutter might have become a prince, and ultimately married the beautiful and mysterious woman. But not so in Japan. Instead, the story is resolved by “the aesthetic solution,” in which the hero is left to contemplate his own existence against the backdrop of a beautiful image. Or maybe I am being too western here. Maybe his existence doesn’t matter. Maybe all we are left with is the beautiful image.

>The Writer’s Journey. The Japanese Psyche: Major Motifs in the Fairy Tales of Japan, by Hayao Kawai

Japan, especially in ancient times, aesthetic value and ethical value were inseparable. Beauty is probably the most important element in understanding Japanese culture. In fairy tales too, beauty places a great role in the construction of the stories. In fact “the Japanese fairy tale tells us that the world is beautiful, and that beauty is complete only if we accept the existence of death.

Thanks for the explanation! That is a fascinating difference to western fairy tales, which are didactic in nature i.e. they always have a teaching to them. I wonder if a game with such a plot would feel very satisfying to play, though.