The point is you don't need the sex scenes to understand the plot or the characters. Of course the book would not serve the same purpose if you took the sex scenes out, because its purpose is to be erotic. But the plot would not actually change at all, and neither would the characterisation, because the plot and the characterisation do not actually rely on graphic sex scenes in order to make sense.
I don't really give a **** if people want to see pixel knockers. What I want is for them to just be damn well honest about it, rather than trying to couch their desires in 'maturity' when, in fact, there is nothing inherently 'mature' about nudity at all. If anything, this obsession with nudity is shallow and juvenile.
To reiterate: the act of including nudity doesn't bother me. The act of clamouring specifically for female nudity (under the guise of making the game more 'mature') does bother me very much, because it is sexist and dishonest and not mature at all.
OK, so you're attacking a straw man. Because I've never yet taken a position on the central topic of the thread -- I haven't said yet whether the game should include sex scenes (although so far the games have done so, and I haven't had a problem with that, it is true), nor how they should be depicted.
To tell honest truth, that 2nd matter in games 1 & 2 has always been kind of irrelevant, because as you might be aware, at least if you play on PC, there exist a number of mods whose precise purpose is to change the presence and appearance of nudity in the game, and how the sex scenes are depicted. Obviously, it would be dishonest to disagree that most move in the direction of greater explicitness. So, if you're not satisfied with what the developers have provided in this area, there are lots of people who are willing to give you a more .... satisfying, experience. Thus, tbh, I really don't engage the 2nd debate, as the existence of mods has always allowed people to tailor this to their taste. Indeed, some would argue there are almost an unhealthy number of mods in this area, but that is a different question, and I think relates to aspects of human nature we prefer to hide or not discuss, but the data support. 
It may be a lot harder to do mods for DAI ... which could change that very equation ... but we digress.
I was only talking about this one question that you engaged by saying that the presence of sex scenes in a work of literature has nothing to do with its plot and characterization. I suppose, but not if your book is about themes like sexual awakening, or sexual freedom. Of course it doesn't have to describe those explicitly, but it might be a little bit like writing a book about the horrors of war, and then leaving details like headless or limbless bodies out, or doing as some people have argued (and I would vehemently disagree with) and taking the word "N**ger" out of every copy of Huckleberry Finn.
If the plot is about a person's sexual awakening, then sexual events ARE part of the PLOT.
Now, BTW, if we're going to discuss something else, which is: have the sexual content of most video games been pitched at the tastes of a certain demographic which is not representative of the population as a whole, has most of it been terribly sexist by showing nude bodies of women but leaving out those of men, is a lot of it "power/conquest fantasy" based for the "Bond hero," and most importantly has the writing for those scenes been closer to a very bad Penthouse Letter or the most amateur of sexual fanfic, rather than aiming for DH Lawrence, well, my answer to all of those questions are yes.
So I guess I would say my answer here is what Candida Royalle says to the porn industry, though I have been treating erotica and porn separately (although there is also an interesting discussion about where the dividing line is there, and we could discuss it) ... she tries to answer the way a lot of porn is made, which from her POV is badly, and make better porn - for both women and men, for couples to enjoy and not just teen males to masturbate to. But to people who say there should be no porn because of the bad ways in which it depicts sex and sensuality, her answer would be to make better porn.
So I guess, leaping now from analogy, if your point is that the sex scenes in video games have mostly been done solely to titillate young post-adolescents, have been done poorly and shallowly, and are incredibly sexist in the way they work, why, yes, I agree on all those points. This is also separate from the "uncanny valley" problem of whether animated, moving 3D rendered humans at this point in time can interact in simulated sexuality (however explicit you want to be in depicting it) in any way that is believable and not silly. (I would say the answer there is iffy, if only because it's a problem limited resources in the world of 3D animation have been devoted to, for obvious reasons.) On the other hand, I would say that might be an argument not for ridding all video games of sex scenes, but trying to figure out a way to do them better.
Now: we come to the $64,000 question. Could Bioware do such scenes? Maybe, but I agree with people who say they never have. Are they capable of it? Well, I hate being unfair to them
but IMHO, not unless a certain design philosophy changes, but from my POV, that philosophy relates to larger matters than just how sensuality is depicted. That philosophy relates to what they are trying to make, and their audience.
1) are they just trying to make Space Invaders, Super Mario Kart, or something that aspires only to be a game, and not art, or like a great foreign film or great graphic novel or a great piece of literature? (See Roger Ebert's famous column on why no video games are worthy of being called art.) If you have a writing team, it strikes me that you are trying to create something that aspires to being like literature. But then, I have to confess, other design decisions they've made recently don't make sense from that point of view.
2) is their game audience solely what most people consider "the core gaming audience" -- young post-adolescent males between around 18 and 24 -- or is it people outside of that frame?
As you may have noticed, I view 1) and 2) as relating to issues that go far beyond how sex is depicted.