Am I wrong though? it's just bizarre dude, everyone else just looks at her funny and they can steal her body, make her blow them, whatever.
Aurora's like Emma, you are feeling horn- *cough cough* oh no my power's run out again! I'll see you in a fucking week.
My guess is that, because this is fairly early into the plot, the story on Emma's pure side would be completely lopsided in favor of the corruption mechanic if they play their cards too early. It would be no fun seeing her one day the pure honor student she is, something snaps, then the next day already a full-blown bimbo. Add the fact that you can't lower corruption (at least, not any way that I'm aware of), and it's clear that it has a place as a plot device for the lewder scenes, albeit having no relation to the story as far as I'm concerned. More like a subplot than anything. Maybe the game will have an ending depending if Aurora manipulated you enough or not. After all, if the progress is dictated by how effectively you can progress within the days, clearing out dungeons and getting stat boosts to clear said dungeons, then there's breathing room to avoid corruption. It's made harder thanks to the situations that Emma has to go through, but there's room for error.
In other words, if Aurora's whole shtick is that you have sessions with her that are dependent on your corruption, then there's a chance that the player chooses to avoid corruption as much as possible and will end up missing on said scenes, perspectives or gameplay changes. This in turn could lead to fewer debuffs or a better ending perhaps. This is already integrated as a plot device that doesn't affect the story (yet) but affects how the MC thinks/acts, which in turn can influence the story. Superficial at first, but if dealt right it is the catalyst for bigger events and forks down the road.
Spitballing here, but it's reasonable enough for her to not be the big bad of the story. Heck, the dungeon leaders are more threatening at implanting suggestions thanks to the afflictions Emma obtains because of the scenarios she's placed in, which in turn could influence her decisions with those familiar scenarios down the road.