Are fully animated sex scenes really necessary in video games? Are people that sex starved in their actual lives? (I know this last question is a bit inflammatory but I'm just baffled by it.)
My belief is that the big difference here is that the person gets to feel like they're involved in the scenes, that the "sex," such as it is, is interactive. That's the difference, and that's the draw. They're not just watching a video; they are a part of it. Or at least, many people *perceive* it this way, even though the person's participation is actually not real.