I agree that the lack of variety with regards to companions is a weakness. If they can't make interesting companions that aren't conventionally attractive, I consider that a shortcoming. But one weakness or shortcoming doesn't tank the entire game, it's just a flaw in an otherwise great production. But when a flaw involves romance or sex, it seems to get blown way out of proportion.
I don't think it gets blown out of proportion.
I think people understate the effects it has.
Like, I've already covered how a focus on sex has lead to lack of variety in companions, it also lead to the character assassination of Halsin who became just a walking sex pest as a result.
But there are other things affected too, like there have always been complaints about how "Thirsty" companions are and how it's hard to simply be friends with companions without them trying to get into your bed because dialogues are overall made with romance in mind (Yes, you can opt to turn people down... But this is still an effect, where in order to get to know a companion you have to keep going through the song and dance of them becoming attracted to you and you then turning them down)
With the main concern being how much of a shift this is from prior Larian titles.
If we look at something like the Witcher games, then sex was a feature of all of the games. It was actually at its peak during the first game where sexual encounters earned you cards depicting the naked woman you slept with. It has always been a feature in the game and it's always been a side aspect rather than a main focus. Even in CDPR's other title, Cyberpunk 2077, then sex remains a very much minor aspect of the game and has little impact on anything besides the romance scenes and a few random sexual encounters you can have with joytoys or BD's, it's all opt-in and has no effect on the NPC's outside of specifically pursuing the romance (Perhaps it affected their design, with all the LI's being pretty but it's harder to say with the lack of ugly main characters overall).
But with Larian games... It's never been a thing in any game until BG3. Where it suddenly starts taking up some of the main focus. With marketing focusing on Bear Sex, with characters being designed around sexual compatibility (Both in terms of being "Normal and pretty" in appearance as well as them being generally pre-disposed to come onto you so long as you're not a complete dick to them) and much of the post-release support being focused around sex and romance.
This 0-100 turn from Larian is disconcerting. Even more so when these things are also incredibly popular aspects of BG3, with Astarion and his romance being THE most discussed aspect of the game. Meaning, if Larian is like most other developers and looking to make something successful... They'd double down on this sexual focus that is the popular part of BG3 and make their new games focus on it too (Potentially even more so), when it shouldn't be the focus of the game, it should be a side aspect.