I think the "why" has to do with trust and potential. Since the author is very transparent about progress and intentions, the public content keeps a consistent good quality update after update, and frankly speaking, the competition isn't exactly perfect either since most games here are indie developments made by people with no prior experience.
People are willing to invest in this game precisely because they trust that it's only going to get better, and even with the current content it might not be much, but it's entertaining and a feast for the eyes.
Also, maybe we have differing opinions in what constitutes a "bleak" story, and that perfectly fine! But from my perspective this game delivers certain amount of finality and satisfaction to the problems MC encounters. He's not the type to sit around doing nothing anymore, so it feels kind of good when we see him prevail and protect his girls, specially since the choices we make matter more than it does in other similar games, you can actually feel and see the consequences along the routes, which is pretty dope if you ask me.