First off, let's be real that there is precious little, if any, *romance* in this game. Sex and romance are most definitely not the same things in any way, and I don't see any romance in the game in any meaningful way. And as an aside, I'd have been quite fine with actual romance in the game, as in any game I play.
But to the question of audiences, it does make sense that Larian would try to cater to the very large group of (mainly younger) gamers out there who want, even crave, a lot of gratuitous nudity and sex in their games. That audience also craves these same things in their TV shows and movies these days. That audience, I dare say, outnumbers the hardcore cRPG fans by at least a margin of 10 to 1. So if you're going to be investing hundreds of millions of dollars making a AAA game, you have to find "creative" ways to boost your prospective audeince if you want to turn a profit. In BG3 Larian did have another ace in the hole, which is that this is a D&D game, and D&D has gained mainstream popularity in recent years. So they did have that going for them in a way that other cRPG IPs do not. But I'd guess Larian wasn't convinced D&D's popularity alone would be enough to carry the day, sales-wise, to match the HUGE expenditures Larian devoted to making this game. So, they needed something else, and that something else was gratuitous nudity and sex.
I'd also note here something I've said before to those who claim people can get plenty of nudity and sex online these days. One cannot underestimate the power and the draw of sex that is interactive, where you can engage with sex objects as you want and in your fantasy scenarios. This is what Larian is delivering with all the nudity and sex in BG3: interactive sex.
Lastly, I've also made this point numerous times, but it needs to be appreciated that the posters here in this forum are a tiny fraction of 1% of whole BG3 player/fan base. As such the forumites here are not, even in the slightest, representative of the overall player base. And yet, even here in this forum, as some of you have noted, most of the discussion centers on "romances," the euphemism for sex. Only a select few posters, the same posters, have shown an interest in talking about the issues in the game hardcore cRPG fans might be expected to care about.