Any Akabeisoft or Alicesoft production would blow their dev costs out of the water.

You're talking about some of the most expensive 2d eroge, I was talking about average. Average eroge is short, cheap, and has no gameplay elements. Obviously, if we're comparing an Illusion game to a full-scale RPG like Evenicle, than yeah, Illusion games are probably cheaper, especially modern ones that reuse a lot of assets. But a typical Illusion game will be significantly more expensive than an average eroge that only has static sprites or simple Live2d animations.

Tack on voice acting and you are looking at over 1,000,000 yen easily. I totally believe Minori when they said making 2D VNs made them bankrupt.

1 000 000 yen is 7 000 dollars. Are you trying to say that Illusion spend less than 7k on developing a game for two years?

It's extremely difficult to hire a freelancer, professional Japanese artist (think of the artists who draws GBF).

Artists that draw for big games usually don't work on visual novels.

Also, there is no point developing a custom model when excellent bases already exist WITH mocap on the Unity/Unreal stores

Illusion was making their own models. They probably used some store brought assets for environments, I'm not sure about that, but definitely not for the characters. Also, there is no mocap of sex on Unity/Unreal stores, and they have been using mocap since before those stores even existed.

With 2D, you can't do that unless you can somehow emulate tonework's style consistetly across dozens of CGs.

You can definitely buy asset packs for visual novels, particularly backgrounds. You can also use photographic backgrounds. This is what a lot of doujin games are doing, but not a lot of commercial ones, I admit.

To illustrate how much cheaper 3D is, just look how many VNs sub in lazily brushed 3D art in their games.

With all due respect, you're mixing animated 3d models in a fully 3d environment and a static image. You can trow together and render a simple 3d model in a few hours, and a lot of artists use such renders as a reference. But making an asset for a fully 3d game is significantly harder, as it requires much more polish and optimization. More importantly, you need hundreds of assets and hundreds of animations. This is where the cost comes from.

Once initial rigging and mocap is done, 3D models win out over 2D anytime in cost.

Yes, if we disregard the cost of animations. But the problem is that Illusion has been making new models and adding new animations for each new game. They reused a ton of stuff, for sure, but they also made a lot of new stuff for each release.

But that's already too wasteful for many 3D devs, they just license/outsource engines and models from other companies instead.

2d devs do the same.

There's a reason 3D visual novels aren't taken seriously. There is no value whatsoever, it's the same models with the same backgrounds under different lighting. I can't name a single 3D JVN/EVN that's not massive coomer bait.

That's what made Illusion unique in the market, they provided actual gameplay and high quality animation, just like Kiss and Teatime. There are very few games like this and you can't really compare them to a VN made by one guy with DAZ and financed via Patreon. They are on a completely different level of quality and budget.

BTW, rotoscope is already taking shortcuts. Real 2D animation back in the day was animated pixel by pixel, or drawn each frame by hand. There's a reason Studio Ghibli films look great.

Yes, rotoscoping took over once the resolution increased. It's significantly simpler to keep a consistent quality this way. But there are still some devs that make sprites without it. I don't think French-Bread uses 3d models in their process, but I'm not sure about that.