I never thought adding an element of immersion would've been this polarizing, but apparently it is...
As for the feedback aspect: the primary issue is that most of what's being offered is redundant considering the whole scene is avoidable, and it doesn't seem to impact the story aside from offering 2 attribute points for each of the 4 attributes. There doesn't seem to be any indication that forgoing these points will negatively impact the story or the player's progress.
This ties into the previous section:
The author seems to be striving for a specific setting - which includes depicting brothels. Just like CPR purposely depicted brothels in the manner that they did in Witcher 3, the devs here are doing the same.
Personally, this topic isn't adding anything constructive to the overall discussion. If a brothel scene is causing this much disappointment, then I highly doubt they're the intended audience.
It is true that we don't have all the information, but the dev has indicated that not only will the elf girl that is already there be coming back but there are many more scenes with whores planned. The dev has said this will be a harem, and one without lesbians, the audience that he seems to want to court are the ones saying they don't enjoy the whore content and will pass it. And if it so irrelevant that it can be skipped entirely and not have an impact on the story then that begs the question... why is it there at all?
You might say because it is part of the theme, as you did, pointing to the Witcher. One difference is that in the Witcher we are playing Geralt, here we are playing a custom Mc. Geralt was jaded, every women he truly loved or cared for had either died or left him, or had other things get in the way, so he found some small comfort in the arms of whores, in part because he was a broken man in many ways. But even there it was a small part of the content, and there were far more scenes with other woman who are with him because they like him and even love him. the Mc is a young man with many prospects, so why is he going to brothels? Why isn't he spending more time with a girl he is courting and actually using his status as a bachelor to work towards a woman that is worthy of his station. He isn't an old man or a broken man with no other options, is he? Is he so horny that he just needs relief, do his powers build up and become painful if he can't bang someone and so he turns to whores because he just can't hold out? Clearly not since he can skip them completely and it might never have any impact on the story... so again, why have it?
For early sex scenes then? Again, there are other ways that would please everyone and not draw any negative feedback.
As far as historical accuracy with a medieval time period, this is something that I know a bit about from almost 20 years of studying history and human nature. Brothels were far less common than they are depicted in media. A big city might have one or two, a midsize city might have one. Small towns wouldn't have one at all you would need to travel to one. It wasn't until the industrial revolution (or Victorian era) that the brothel as often envisioned came about and even there it wasn't all Moulin Rouge and Old West Town style, it was still relegated to larger cities. Taverns and brothels were separate things, and while some tavern girls might have some customers that they got on with and even entertained on the side, it wasn't common and they were decidedly not whores open for anyone with coin, they were often either the wife or daughter of the tavern owner and if they weren't married they would be interested in finding a husband, not banging random strangers.
I also happen to think there has been several people offering constructive feedback. And again, that if the intended audience is harem fans, then them voicing their opinion should count a little more than all the people who would be happy either way. It might be true that the average player would be happy either way, that some 60% will play the game regardless. But that other 40% is often where the split is and courting one often cuts out the other, so hearing from the one you might want of the two to get as close to a 100% of the fan base as possible is never a bad thing.
EDIT: One of the great things about Ren'Py is how easy it is to change dialog. The visuals could probably all be kept exactly the same, but the dialog changed with little effort.