Well, it's very complicated to answer without derailing the thread, but the sexualized women in The Witcher 3 have character depth but no real reason for the sexuality, making them pretty much window dressing to appeal to a male audience in spite of their actual good characterization usually. Nier Automata on the other hand did it completely shamelessly (as in, they didn't try to Kojima their way out or hand wave it away, literally the creator just said "I like sexy women, so I made 2B sexy" or something along those lines) but also had symbolic reasons for why the female androids are somewhat sexualized (and also sexualized the male villains having them be shirtless and buff as well). Ultimately, I think it comes down to the execution and where The Witcher 3 continued sexualizing the characters, Nier only really does so on a surface level
Not entirely true, considering the sorceresses and their motivations.
In the Witcher universe, mages can alter their appearance. Mages court kings and other powerful figures, and using an attractive body can help them politically.
Now, I would actually like this lore if it wasn't just used as an excuse to make all the female mages sexy.
Depending on the situation they were involved in, they could use all kinds of forms. Sex appeal wouldn't always be a strength in a political situation, perhaps age to show wisdom, or heavier frame to show strength in a different culture, etc... they could easily have used this lore point to show a diverse range of positive representation for body types, and because it would have been diverse the slim/slender ones would have been a part of this positive representation as people like that do exist... they're just not EVERY single woman.
This is a fantasy setting, and it becomes less immersive the more it leans into the fantasy's of a specific userbase instead of the incredible diversity an imaginative fantasy setting allows.
This limitation they placed on themselves actively harmed their characters, imo, even if you could make an argument that they're well written and interesting overall... they could have potentially been even more interesting.