I have yet to see AI art done well with VNs, but I see your hypotheticals, and would be happy to break it down just like the edited post.
But before I start, I will say I dislike AI art on a personal level, it has a suprisingly long way to go before I feel it could match your best case scenario, just by the nature of how it works.
1-1: If AI could be perfected, was consistent, didn't add unrelated content, and wasn't too busy; ie. if AI was indistinguishable from the work of a person, I wouldn't notice, let alone be able to argue against it. I don't really pay for most of the VNs I read, so it's not even like I'd be supporting the ecological side of things, even. So I guess I'd be ok with it.
1-2: I do think, in that hypothetical "ideal AI" setup, that my instinct would be to prefer that over asset swap; because I've started noticing "the same" characters in various novels, and it's mildly annoyed my subconscious, even though I thoroughly understand when I think aboit it seriously.
1-3: I have disliked all the Photo VNs I've seen; I prefer just written, non visual smut to photographic VNs.
1-4: I'm not familiar enough yet with DAZ to know, but I'm pretty sure some of the VNs I enjoy are DAZ, so I'm picking that for this one.
1-5: No no, hand drawn all the way. I've enjoyed hand drawn stuff, even when it's mostly simple.
2: I've poked at prompts once, enough to get the gist of how it works. I wasn't a fan, and while things have improved, it's been small improvements, not massive. AI is improving quickly, but only in very specific ways, and in others it's stagnating. I feel there are some breakthroughs needed to truly get anywhere close to your hypothetical "perfect" AI art scenario.
3-1: I do prefer 3d models, and I actually can't say why. I prefer them even when a VN has no animation, which is even odder I know. For some reason, the uncanny valley doesn't really bother me in this specific aspect. Perhaps because it helps me detach a bit from some of the less ideal aspects of VN stories.
3-2: AI video can't 'remember' anything several frames prior that is off screen; there's no way this is happening anytime soon. However, in your "perfect" scenario, I would view it the same as the perfect still image scenario; I likely wouldn't notice. But I'll say right now that I've seen animation techniques in some of my favorite VNs (not even sex scenes) that have floored me and felt very bespoke. You won't get bespoke with AI, ever. It's against the very idea of AI.
4-1: Oddly, no. Even the heavily anime themed 3D models, like Honey Select have been fun to see used. I don't mind cell shading, anime theming, but I also don't mind an attempt at realism, or attempting to match film.
Maybe it's all the gaming; the same reason some people really like Overwatch porn.
4-2:As I said previously, the style doesn't determine how much I like it.
Alright, now to throw in my two cents separate from the questions.
The biggest thing to realize is that this is a subjective decision, people like what they like. So some people will LOVE the overly detailed, yet incoherent AI art of today for their porn. Some people instead love something that a lot of work has been put into. And some people couldn't give a damn about visuals, and it's /all/ about the writing. for me, I need a good mix of writing and visual, which means finding VNs I really love is hard; and I seem to gravitate towards the weird and funny for some ungodly reason. Ah well, my brain likes what it likes.
I don't think it's fair to think the majority of any group likes or dislikes a style, even AI; and other than the way this forum incentivizes posting, you'll tend to only get vocal minorities screaming into the void. (I would so be lurking only if I didn't want to one day get enough points for some VNs that are behind the plus)
So my reasons, won't jive with a ot of other people's. One day, AI will likely get to a point where it can be "perfect", but I think I'll always prefer the kookiness of humans making my lewd stories.