Here's my current DF cycle: I view the devlog each day. After a release I just intrinsically "know" the game is completely unplayable for 2+ months because, well, it just is.
I don't think I'm alone. I'd go so far as to say this is 'the norm'.
This is 2016. The idea of a solo dev just doing his thing and coding out a game isn't a novel idea anymore. DF runs the risk of being left behind. It's ok to acknowledge that fear.
I snipped your quote down to the points I disagree with. DF can't be left behind because it's not in the running. There's no compulsion to make a profit, meaning there's no real issue if playerbase dwindles (which it won't). The devs survive of donations, sure, but thats way different from a corporate project's need for projected profit.
I find the new updates playable because they just are.
And it's alright to be afraid but projecting that fear onto the entire playerbase seems a bit silly.
I was also the guy who said those things about the "mythology" of df's gameplay, but I said them for a different reason than you thought. The "correct" way to play DF is to generate these myths on the fly while you play, using your own imagination to construct additional narrative. A side effect of this style of play is that people misinterpret DF-based stories as entirely game-derived. To see this in action, go read Boatmurdered or some equally famous story and list out the things that actually happened in game, vs. those things that were made up for the story. That fortress was great not because of the DF game engine but because of the awesome writers and their narrative tone. The catch is that without DF they would have nothing to write about.
It's pretty much a personal opinion, but I doubt DF will ever reach the point where it can completely replace that human creativity. If you play this game for it's simulation aspects you will probably be disappointed by the interface, the bugs, and the incomplete gameplay. If you play as if it was some magical, infinitely devourable fact-fractal from which to glean inspiration then there's not much to complain about.