The genesis of this was reading the following by Splitter of Chocolate Syrup Waffles (via Author, who quoted it in his roundup):

[...] After getting everything off her chest, [Kirino] gives the best moment of the series where she chastises her brother for thinking the things she enjoys in 2D is something she wants to experience in 3D. This works on so many levels.

For me, one of the interesting things about Kirino is what I'll call her otaku blindness. This is most obvious in the scene where she shows Kyousuke her collection and immediately starts talking to him as if he was a fellow otaku as opposed to a disoriented outsider being overwhelmed by a flood of information he has little to no context for; a blindness to how he is different from her and doesn't see things the way she does. This otaku behavior is so common that it's almost a cliche.

However, I think that her blindness goes deeper than that. In particular, I believe that she is sincere about why she collects and plays her eroge games; she plays them for the story and because she thinks little sisters (at least as they are in the games) are cute. She is immersed enough in her enthusiasms that she is effectively blind to the eroge/R-17 components; she knows that they exist but she's desensitized to them and their implications, in much the same way that long time anime viewers can become more or less blind to fanservice.

Getting back to Splitter's remark, I thus wouldn't say that she enjoys this aspect in 2D as such; instead she's just null to it. Kyousuke can prod her back into an awareness of it but he has to do so explicitly by things like reminding her about the (nominal) implications of him playing through R-17 portions in front of her, and until he does so it seems that the issue simply hadn't occurred to her.

(Kirino is clearly not innocent about the eroge nature of her stuff, given that she carefully hides an eroge game inside a harmless case instead of leaving it in its own case. What she was doing carrying the game around in her purse at all is a question that may get answered later.)

PS: I am aware that this is one of the least creepy interpretations possible of OreImo's basic premise. As an optimist, that's why I like it.