There are two reasons at the root of the "No Porn Games" phenomenon in America.
1. Christianity.
For some reason, the church seems to have drawn the (mistaken) conclusion that God never intended us to reproduce (referring to the Garden of Eden fiasco). Therefore, sex, of any kind, is an affront against God, and two people are only allowed to have sex if they have been joined together (at least symbolically) "in one body" by a priest or other religious leader performing the sacred rite of marriage (in which case damnable sex is reduced to somewhat less damnable masturbation... I guess). And even then, if you're a Catholic, you have to let the priest wash your love juices off your newborn's body before they qualify for salvation; guess the angels are all such prissy fucks that they won't even touch you if you had pussy juice on you at one point, let alone "carry you home."
Don't get me wrong, there are plenty off good reasons why premarital sex is a bad idea, most of them having to do with unwanted children and the spread of STDs. I can imagine that in the days when the bible was written, before nice things like healthcare and child support and before we knew what viruses and condoms were, the wise people were acutely aware of these problems and saw a religious text as a good opportunity to beat some wisdom into people's thick, pre-science heads.
But back to games, since God is omnipotent, and can see your thoughts, and because all his angels tend to faint like old women when they see your fantasies about beating off on a pair of double-d breasts on the DeityVision (TM), and because somehow the people who run Christianity are 100% absolutely, positively, cross-my-heart-and-hope-to-die CERTAIN of all this, the church leaders of the world have taken it upon themselves to keep you from thinking about sex EVER for your entire life; ideally, even during the one (two or three at the max, depending on desired family size) time(s) you're actually having sex (with your wife/husband and for purposes of procreation only, of course).
2.
Um... crap. It took me so long to write that last wall of text that I actually forgot what the second one was supposed to be. So let's just say it's slippery-slope media sensationalism. To give due credit to previous arguments, let's call this the "Mass Erect Phenomenon".
You know what I'm talking about. It was mentioned in the article, for Chri... (whoops, almost forgot about the DeityVision (TM)) goodness' sake. I think Yahtzee described their feelings best when he said they thought Mass Effect was a "child-corrupting boob extravaganza".
Basically, some (mostly Christian, I'd imagine) parents are worried that their (male) children are all going to turn into slavering rapists if a game shows them so much as a pubic hair. Obviously (in the vast majority of cases, anyway) this isn't true. Even the worst examples of sex in games, Japanese rape sims, are far worse than the porn games most people would want to play. Via the Mass Erect Phenomenon, Japan must therefore be the rape capital of the world, right? NO! Japan's per-capita rape rate was 1.85 in 2002, vs. 32.99 for the United States (according to a UN survey). Good job keeping people out of HELL, Christianity!
Anyway, since Christianity will always be the dominant religious group in the U.S., and because Fox News will always be staffed by panicky nut job Mass Erectors, we can expect adult games to never exist outside of sketchy websites and Japan (and maybe not even there, if current trends continue).
Now, if you'll excuse me, I'm going to go play RapeLay for an hour... to make the angels have to change their trousers.
