My only qualm with the side-characters being used as a "buffer" to provide some sexual content while waiting for things to progress far enough with the main four ladies is that I think it really softens the blow of things changing over time. Like one of the things that NTRPG2 really nailed for me was how it turned a quaint, quiet little village into a depraved nightmare where everyone — men and women alike — became their worst selves.
But while things could certainly ramp up the intensity for Luminia, I feel like it just won't be able to hit quite the same. It would've been nice to see more of a pronounced divide between how the city was during the innocence of Leto's childhood under the reign of Rose's parents, and seeing the moral decay start to set in with the Duke in charge. But aside from the casern with the militia taking control, I can't say that the city feels much different so far. You have a few more little events happening in the background with some of the minor NPCs, but they don't really feel like an escalation when you already the same things happening so early on in the story. They're more like isolated coincidences than a pattern.
I mean, just as one example... It's been a few months since I played through the prologue (instead of just picking up where I left off with the most recent update) so I might be incorrect, but I'm pretty sure that one of the buildings at the top of the map near Haylen's church was always implied to be a brothel from the moment that Leto first arrived. Which seems like such a missed opportunity to convey how the city is becoming more like a slum.