As of this game I highly doubt Illgames have good programmers. They had programmers when they were using their own game engine. Then Illusion started using Unity engine; "Sexy Beach Premium Resort" happened and it all went downhill from there...
Now animators responsible for H animations are doing better and better with each game. But when it comes to coding a good game... it's just really lacking.
I think they hit the wall of their own engine. They want a free-roaming, open world games that have a "modern" looks and feel with updated shader and better performance, something they lack on their own old game engine (If you follow their their story, even at that time people are complaining about the poor performance of their games, slow loading and stuttering on some of their old games).
So rather than "upgrading" their own engine (something that might takes years to complete and takes a lot of resources), they look at the alternatives, see Unity pricing, and goes all-in on that shiny, modern games engine. It's regrettable but we can see the reasoning. With how fast Illusion producing games, waiting for the programmers to complete the upgrades of their old engine (from DX9 to DX10 with all the updated shader) will take a big hit on their income. Also converting to Unity open the door for Illusion to much broader talent pool (at that time there's already many people learning Unity in college) and much faster game development because fresh graduate doesn't need to learn their proprietary game engine.
SB Premium Resort is a flop thought. Too big, too ambitious, but plagued with the same slow loading problem and jankiness of their own game engines (Des Blood 4 and Yuusha kara games comes to mind). Understandable because it's their first open world games with Unity (they used Unity since Playclub). But yeah, it leaves a bitter taste for Illusion as they killed the beloved Sexy Beach series because of it.
What's funny though is that Artificial Academy 2 is build on their old engines and it's fast AF and can sustain many characters in one screen. It's their last open world games done with their own engine. If only SB Premium Resort is build with that we might see Sexy Beach 4 on our timeline...
For one thing, I do believe compared to Illusion, ILLGAMES feels like a massive downgrade when look at writing. I mean Illusion didn't well either, but somehow worse. and Context always plays good role to immerse.
I don't think it's a downgrade per-se, but more of a restriction of their own direction. They wanted to make a games that's "safe" so they avoid the extreme end of any human interaction. Their conversation avoid showing harsh words, so even the "yandere" characters doesn't feel intimidating at all, and any scheming and cheating doesn't feel impactful. You will see a STARK contrast on characters interaction between SVS and Artificial Academy 2. On AA2 you can feel the impact when a characters is angry, annoyed, sad, or depressed, not only on their blunt words, but also reflected on their face and body animation. While it's all void on SVS.