In my opinion, it is because this game has an identity crisis. From the plot synopsis, you would think the main character is a very bad guy who is tricking/forcing his students into sexual servitude in his new club. The game strongly suggests that it would inherently have very dark themes inside (non-con, blackmailed, forced prostitution, etc…).
However, this was not the way the developer wanted to take the game. Instead, he has tried to have the game focus on more “love” routes and has tried to avoid the non-con aspect of his game by focusing on corruption.
This creates a problem. The club was billed as the main attraction of the game but there is no way to plausibly have the girls participate without unscrupulous means. So the game has focused on a million other “dates” and other activities to try to alleviate the problem the club causes.
Many still enjoy the game the way it has gone and the developer seems happy so I wouldn’t expect anything to change in this regards. As the plot lines become more fleshed out it becomes more plausible to begin adding true club activities.
Well, I don't think you're completely wrong, but not completely correct either. You can always guess and assume what my intentions are, but truth be told, they're not always that clear to me either

but I've been focusing on the "love" routes and stuff outside the club because I prefer to know the girls I'm corrupting. Sure, not every game has to have more to the characters than just escalating porn scenes, but I kinda wanted there to be more to them. Hence the porn parts are still very much in the works.
What's probably more true that this game has issues with pacing and lack of content. They kinda stem from the same reason - overly ambitious first solo project.
I gave up on it, after playing the original release, where it showed far more corruption. Even in the next few releases, it suggested it as you have explained and commented. Thank you. Now it's pointlessly drifted into very soft core themes that are a very tedious grind, and lack much content. It might've been.
It might one day be again, maybe. Depends on who you ask.
I don't understand why nothing happens in this club or theme or content.
If it was the title of an erotic book more Porn would be happening in it.
Instead it's a dating game. And it's a bad comparison. You train the girls with hard core and the club is absolutely soft core. Nothing much happens in it. Train them with pointless skills to get very soft core scene if any. Instead you date the girls and you get vanilla sex scenes and they're largely with Lilth or something anyway.
I don't understand this game and why it did this?
Read above, but basically it's the issue that I don't want a hard cut from innocent girls to hardcore pimping. That ride has to feel smooth. And I want people to get a feel of the girls so they're not just any random girls off the street that they're pimping - for that you could play any of the weird isekai whore hotel games where you recruit random fandom girls and unlock random fanart shots of them.