Wow, this post puts some of mine to shame for thoroughness. Love it! Let me dig in here.
Glad you're enjoying the non-sex battle mechanics so far. IMHO they're still fairly simple, and that's largely an artifact of me not being an RPG nerd. And also, as I've said elsewhere, I feel difficulty and complexity in a game like this has a sweet spot: it needs to be a LITTLE challenging, so it doesn't become boring, and so you can bring elements of the narrative and characters into it (hyenas do small damage, but they do it fast, they go down quicker but there are more of them, etc). But not overly complex, because that distracts from just enjoying the game. I'm glad what I've got so far is jiving with you.
A few thoughts on the puzzle idea. I'm actually a big fan of "real hypnosis" too, and what's in the games definitely isn't that. But that's a deliberate decision: real trance guidance takes two to five minutes at least, and I don't even want to think about the nightmare that would be trying to squeeze that into RPGMaker's nightmarish text formatting.
Of course that's the extreme end. It's obviously a spectrum, and I do try to push what's in the games beyond just "and then mind control." The fun of this kink is the process, and I do spend a fair amount of time in the proper scenes dwelling on the experience rather than just the bare bones of what's happening.
Here's the thing with battle mechanics though: they've got to keep moving. My original plan for the new GT stuff was even more elaborate. The general idea is that GT is about learning SERVICE rather than SUBMISSION like CS1 was about, and to that end there was this whole elaborate element of turning the battles into whoring sessions. But it DRAAAAGED way too much in practice, and the initial draft was also too...voluntary, which sucked some of the fun out of it. There has to be that loss of control, that floor-dropping-out moment. I was actually concerned that even what ended up in the game might be a bit much for some people, but I think the game moves fast enough that the amount of time you spend with the mechanic isn't TOO bad, isn't enough to make it start to feel annoying or samey.
So that's one of the big reasons I avoided doing anything overly complex. I don't want it to drag, and I don't want the sex mechanics to be overly complicated, any more that I want the normal fight mechanics to be overly complicated. I want the whole thing to flow, for it all to be fairly intuitive for anyone with a reasonable amount of functioning neurons, without needing a tutorial. IMHO if your mechanics need a tutorial, you've failed (at least for the kind of game I'm trying to make). No one wants to read a manual for a sex game. I realize what you're suggesting isn't SUPER complex, but it is still another layer.
Another reason is that any of these mechanics implemented have to fit with the flow of the story and character. Minigames as I'm envisioning them would be a little too abstract, though there might be possibilities if done in a really clever way.
And third, I'm not a super fancy programmer. Most of the stuff in the game is just clicking plugins together like lego bricks (though I DID make something I'm pretty proud of that will hopefully be in the first content pack). So doing anything in battle mechanics beyond the basics gets to be tricky fast.
That said, it is in the back of my mind. I saw an explicit fan-made Undertale fight recently that was...wild. And while I doubt I'll be doing anything that elaborate, it does give some good inspiration. We'll see what develops in the future. To be clear though, fight system for GT is probably in its final form (at least the main one).