timppu: Natural as it is, it would still feel odd and out of place,
Could it be that it would feel odd simply due to the fact that you see it so rarely, rather than the subject itself? For me, it feels odd when sex
isn't part of stories, as it seems conspicuously missing. I really dislike all the permanent underwear that games give characters, as that really stands out to me, much more so than an orc army, a starship, or a wizard casting spells. The Better Bodies mod which added genitals to Morrowind was a breath of fresh air to me. It wasn't because it turned me on or served as wanking fodder, but because FINALLY I could see normal looking people. The underwear, and the censorship it represents, detracts from games for me personally.
In a similar vein, never mentioning sex, never making sexual jokes or comments in dialog, never having anybody express sexual attraction to another NPC is a constant reminder to me of the politics and pedo-paranoia and censorship that dominates US media, and inhibits my suspension of disbelief. Because I can't really immerse myself in the game world, it is less enjoyable to me. Still enjoyable, don't misunderstand me, but less than it could be.