I do agree that you will get better effect to let the player's imagination fill in the blanks, than to overtly describe these events.
But the concept that Americans are too sensitve? Hogwash.
I agree with you with first sentance.
But what comes to american style of rpg there still lingers some little issue. Violence is good, sex is BAD. And that's american. European rpg:s what I've played didn't shy away form that subject. It's after all related to quite important human passion and motivation. I use to play this rpg from Sweden named Kult. When american publisher got their hands on it they cencorerd few things away. Namely "God" being dead and some sexual elements.
I can totally understand understand not wanting play out details of gory killings, torture or having sex with someone.
But too much detail is different thing than...
Time after time reading some modeule with "bordello, pleasure palace", and instead of whores or releted things, you get to meet (really creepy) undead/ abarrations. Lust is more often than not translated into ugly thing wanting to suck your blood. In totally non-seductive way too.
I like creepy undead/aberrations a lot, it's not that. I just don't like that they are taking over every theme that should relate to little bit erotic. It doesn't make sense when Runelord of Lust (from pathfinder series) seems to the be only totally off from her stated sin, what comes to dungeon inhabitants (lust-spawns I am looking at you). And her chosen school was enchantements, yeh right.
I don't want carnal pleasures glorified in rpgs, i just want them to exist, being implied and hanging in background. Or then they get on creepy and monsterous side. let's say movie called "Dagon", for referance. Not an american movie mind you.
It's bit related to another issue, while comic-books got more mature/realistic what comes to character relationships and villains, D&D is still hanging at 70-80's. Villains are that way cartoonish more often than not.
Even with Twin Peaks or HBO, american morals are still getting in way of mature content. It's limited group of people having cable with HBO and watching showns like Rome or Borgians. Majority don't watch such shows.
Games are still considered for children. Nakedness in computer games gets censored more often than extreme violence. Sex is rated higher in mature angle than shooting and killing. It gets your game a mature stamp which mostly porn games have and that hurts sales really bad. And it can just be pair of t**s in one scene.
That's why in Dragon Age "romance" scenes characters had clothes on, and not too revealing clothes at that.
So most companies in america who make games/computer games don't want "for adults only" stamp. Because generally it's kids/teens/their parents that buy those games.
Slightly off-topic. But it boils down to this. No matter how dark is too dark or not too dark for you, or not enough for you, to publisher what matters is...
It's too dark, when it hurts the sales.