But I do think people who introduce such elements into their group need to be very careful.
We agree on that.
I will admit there are times when it is appropriate, even required by the story to address it in some way. But this is very rare.
This is one place where our experience varies.
1) By your own example, you are reducing sex to rolls. You have players make rolls for things like contraception/pregnancy.
Actually, my player sought out that text for rolls on contraception and pregnancy. She didn't want me or herself deciding such things, for some reason. But if you think that because my player made rolls for
pregnancy that I'm reducing
sex to rolls, well, you're conflating two very different things.
Basically, I see nothing wrong with replacing DM fiat for pregnancy, as DM fiat comes awfully close to the DM punishing the player for their character having sex. If the player knows the rules and has access to medicinal herbs and other contraceptives, that's vastly superior to DM fiat.
Think of it this way, by analogy: In DnD, the player decides whether to enter combat, under what circumstances they will do so, and uses that narrative event to further role play the character and advance the story. But the dice add the spice of randomness and risk to that decision.
Similarly, my players decide on whether and how to enter into mature adult relationships and use that narrative event to further flesh out the character and advance the story. Dice add the spice of risk to that decision.
Just because I use dice to partially determine the consequences of combat, doesn't mean I have reduced combat to die-rolling, any more than using dice reduces social interactions to die-rolling.
If you use bluff, diplomacy, intimidate, and sense motive skill checks to determine the success or failure of a player's RP decisions, then there really should not be any problem with having sex be another social interaction skill check. Having a diplomacy score does not eliminate role playing from the table.
Unless you do diceless skill checks, the problem is with talking about sex at all, not the use of a mechanic.
Personally, by the example you have sighted, I would be uncomfrotable playing at the table with your group. For a few reasons. I do not want to listen to other people at the table describe sexual encounters with NPCs. ... And too often (and again i am not assuming your group does this), it hits either the extreme of being a source of humor or arousal for people. Both are problematic. If people are giggling over pregnancy rolls or midnight trysts, well, that isn't a mature way to handle mature content. On the other end, I have had DMs and Players who dwell on the sensual. This really makes me uncomfortable. I cannot say this enough. It is not the kind of role playing I want to engage in. Others might and that is fine. But too often people at the table, assume silence means I don't object. The default assumption by DMS should be no one at the table is comfortable with mature content, unless they ask them privately.
So long as you're not saying that I'm engaging in badwrongfun, I have no problem with your admission that you don't want that at your table.
Of course, you're engaging in binary thinking. It can be in the game without being at the table. It's very easy to make this easy on other players. For example, you could role play it out via email or instant messaging, telling the player at the table that you're going to cut away from that scene and restart other action while you're together. Solo adventures, ahem, are very rarely entertaining to the other players at the table, whether it's scouting, shopping, drinking, politicking or carnal pursuits. Alternatively, you could just have the player write a journal entry about it after making the relevant skill checks. (One game I'm in rewards character journals with action points.)
I can understand your visceral reaction. Fan service in Paizo's gaming materials--and the reaction at Paizo's boards to said fan service--annoys the holy crap out of me. It drives me up the wall, especially when some posters start fantasizing about swimsuit calendars. (Actual thread, I kid you not.) It feels adolescent, leering, predatory and incredibly sad. Trust me when I say that I try to avoid that kind of thing at my tables.
I feel obligated to ask a rhetorical question, however. You say that people getting excited by or giggling over sex at the table would be off-putting. But don't people typically laugh or get pumped at hard core violence at DnD tables fairly regularly? Don't we design righteous quests and save-the-world narratives to justify that kind of behavior?
Why do we choose not to make the same effort to justify including sex at the game table? Is it inherently off-putting, or are we just not as practiced at telling those kinds of tales?
After all, the sex instinct is just as powerful as the death instinct. One would think that stories that included both would be more satisfying than those that include one or the other.