As I happen to associate with a lot of Transgendered persons, I guess in a sense this may be true. However, Pre-op, in the sense of Transgender or gender dysforia woudl mean that one's biological gender would not match one's psychological gender. As this is not the case for the vast majority of people, and Pre-op seems to indicate that gender reassignment is needed to feel at home in one's own body, then it is also, in a sense, not true for most people.

There is an interesting short science fiction story, "Picnic On Far-Side", which imagines a world where people can changte genders back and forth. It is nto the main driving force of the story, but just a part of the created background reality. I think the author was Francis Jose Farmer. Anyway, I doubt that humans would devlop into such a gender fluid mentality as portrayed in the story, but I can see how if we did, it would seem more desirable for Trans persons and women.