Are you telling me that if you had the opportunity to bring your fantasies to life, you would miss out on it? I think people like us could do very well if such simulations, be it VR or robotics, were available. Just the thought of physically holding my waifu is enough to convince me that maybe it wouldn't be such a bad idea.
Also, since when has the concept of a waifu ever been restricted to non-technological entities? (Sal9000 being a prime example of what I'm referring to) Just because they exist in our minds, it doesn't mean we'd be unable to project our concept of them onto an appropriate physical or virtual form; in fact, I believe we would be able to do so, much more easily than you might think.
I can understand such technologies might never succeed in accurately representing your waifu or in making her feel any more real than how you currently perceive her, but until such things come to exist, there's just no way to know.
We can't be sure what the future will hold, so I'm giving my opinions with an optimistic view, even if I honestly doubt we'll be around to witness it at its best. I highly doubt that at an age when “they're so advanced that typical androids are indistinguishable” from regular humans, that they'd be emotionless machines. But then again, we'd be dwelling into the topics of sentience and self-awareness, something even experts are very much divided on.
You're right when you say that replicating a character's spirit and behaviour would be a difficult task, but, at the end of the day, surely what you see in your waifu isn't entirely depicted in her source material? What I mean to say is that you'll have 'filled in the gaps', so to speak, in order to complete this perfect concept you adore so much. So, in this case, my question is: why would the creation of an android/virtual form with those determined personality traits be so complicated? Again, I'm approaching this from the hypothetical point of view that we'd be so advanced that strong AI (that is, AI that at least matches human intelligence) is available.