A tad off topic, but what did you think of Change! ?
I thought it was not as good as Maybe-Soft's Henshin, but easily the best erotic VN of the year so far.
Anyway, being an actual girl would break nearly every perfection of that is created in the 2D idealization. Besides, how can you objectify the purity of something when the object is yourself?
The Perfect 2D Girl, the Waifu, is made as an unattainable standard. We feel safe and content in yearning in it, idolizing it, because we know that delusion can only bring us closer to it and its reality, and in doing so, farther away from our own. To become this would instantly corrupt and normalize its existence, and the character would die with our shift in perspective.
Only the greatest of narcissists could ignore it all and still gain satisfaction from this scenario.