You are jesting but there are a bunch of Sims mods that focus on making the game more challenging. ^^
Apart from that I have the impression that prettifying mods are in general the most on demand "QoL" mods not just for BG3. I do like the game for more than my lovely pixelfriends but I still like to give them nice clothing in pretty colours once I find suitable stuff, it reflects the progress of their journey. Proclaiming your love for that one character and still going out of your way to put him in skimpy clothing at the first opportunity is where it looses me.
There are also lots of mods for Sims which are explicitly sexual.
Yes cosmetic mods are a feature of most RPG modding but it is the ratio of cosmetic to non-cosmetic which tells the tale.
Maybe it just tells you how much easier it is to make a cosmetic mod, compared to a "systemic" mod. I 'm not a modder, but I'm just guessing that adding some hairstyles or clothings from the game to the character creation would be easier than improving the camera motion or the party's group-movement , let alone the storyline.
