I would also like an explanation. Everyone says that it's actually because of the coding itself. It's so bad, it takes several months before it can even be released -- in whatever current alpha stage it happens to be in. But I don't have an explanation for the art however.
Look, I'll be honest. The code for this game is a mess. But here's the thing. It's not that much more of a most than most Ren'Py games. I've definitely seen worse and I've seen better. In fact, the better ones are either games that a) a lot more simple b) that hired an actual programmer c) just starting out. This game is old. Not like "Oh, this is so last generation." But the older a code base is, the more likely you'll get cluttered code among other things. This is why the Y2K bug was such a problem and they had to find people that knew COBOL in the late 90's to fix the issue. This is one of the reasons why MS abandoned the core for the Windows NT line of operating systems. To the common people, code is just code. You write it, it works, and you're done. But coding and programming is a whole cycle. You have to worry about organization, speed, efficiency, upgrades, code fixes, resource management, connectivity, error handling and a whole bunch more that I don't remember off the top of my head at the moment (security, attack vectors, compatibility, set theory, resiliency... I can keep going on).
If Oni's not a programmer when he started the game, the code's gonna get cluttered. In fact, a code base that runs after, close to 10 years for a first time programmer is pretty good. People can shit on his code and I can understand why. But as a programmer, I know that most people, including the ones shitting on the code, if they were to make something that has lasted close to 10 years would do just as bad or worse. I mean, look at Big Brother or Corruption or Witch Trainer Silver (The original/Akabur's code wasn't bad. But the game play was also much simpler) or Innocent Witches. All those version 1 version 2 stories in Innocent Witches? It's partially done because the code couldn't have been changed without messing things up. AKA, bad code. And Innocent Witches has a team behind it.
Like, there's a way to fix this so that it is easier to get updates and be less buggy, but it requires a completely new way of thinking and coding than Oni, or, quite frankly, most non-coders think. And that refactoring takes time. Like, a lot of time. And he probably can't spare the time/energy/etc. for it. Hell, most large companies don't either.
If you want to learn more, read up on the software development cycle, technical debt and then read up about how many large, very large companies frequently ignore technical debt until it blows up in their faces. I've literally seen entire companies fail due to this. And, in one case, someone even took their own life over it.
Addendum: I wanted to give a shout out to the ren'py game that's programmed better than most other ren'py games. Like WAAAAY better.
https://f95zone.to/threads/vae-victis-khan-conquer-ravish-breed-v0-10-9-doorknob22.74639/
Not only is the game itself good, but the code is well organized, human read-able and even going through actual refactoring to prevent future problems. I'm not saying all games need to have this level of coding, but I think it should be noted and appreciated when it does.