This conversation is making me realize that our contemporary desire for a completed game is a carry over from 19th century patronage traditions. Like 19th century patrons we want something we can hang in the dining room already, and call our own. Like them, we value artworks both for themselves, and for what control over them represents for us. It all reminds me when Manet painted some asparagus
for a patron, who compained about the painting being too small for the price. So Manet painted him a tiny bit of Asparagus to "make up the difference in weight"
We are the same with our nitpicks, and much like Manet, Toady gives us a sprig of asparagus at a time. Unlike 19th century patrons we are dealing with a novel art form that never results in a singular, significant object anyone can truly claim to own.
If Tarn Adams spends his entire life never finishing dwarf fortress, it will still be an artistically significant game and an important project for the art history books, but it couldn't be conclusively finished (there could always be new goals) and still encompasses all the prior unfinished versions as parts of itself. That it is unfinished it good. The Mona Lisa and the Last Supper are also unfinished.
The end is like the "inevitable death" ending in Stanley Parable: finished but very ossified, a museum installation instead of a game.