For me, the explanation is that on a general level it's no problem to talk about sex, I'd say the Western society is very open about it - but on a personal level, sex as an experience is reserved for the individual alone. And normally I don't want a story to cross my intimacy barrier by showing me explicit sex scenes, because it's simply discomforting.
Another thing about this is that, concerning the "solution" of having two versions, as a Westerner, I will instantly ask WHY there are two versions - one all ages and one 18+. To me this sends a clear signal that sex isn't necessary in the story and because sex is such a powerful and intimate element, I will (rightfully) assume, it was never an integral part of the vision to have sex in the story. While this is fine for the Japanese, who are able to enjoy multiple elements separately within one presentation (the crazy switches from comedy to deadly seriousness in many anime), the Western culture typically appreciates fluidity and consistent style - and so, sex that can be taken out, acting as an add-on, will for the Western audience feel useless, irritating, inconsistent, shallow and pull down the whole vision/project.
So my counter-question would be whether the OELVN scene needs to consider the ero-nonero equation at all - for which I have an answer - it doesn't. If a developer feels that sex is necessary, he will put it there, but even so, in 99.99% of the cases, you can still have a soft representation of sex (erotica, or implied sex), for a story you don't really need explicit porn.
Therefore if you cross that barrier of explicit sex (in a game that is story oriented), you better have an excellent reason. The Western fans are sensitive when you want to present them something directly arousing - as for most of the time they want to enjoy sex separated from any other experiences.
The others have already commented of course, but just to join them, I think it's good, because it's more natural not to have ero versions of stories in OELVNs. We often talk about how it's not so good to just copy everything from the Japanese original - well, this ero approach is something NOT to copy.DaFool wrote:... OELVNs are decidedly non-ero... maybe that's good?