Medical issues having to do with those body functions have been systematically devalued. Why? Because women are the ones who typically have those body functions, and women were not considered important. “Women’s health” is the rallying banner under which proper attention has been marshaled.

"Let's throw that all away!" you say, gleefully. "It's dehumanizing!"

No, it's the exact opposite for most cis women. It's a strategy that has been simultaneously humanizing and effective at getting appropriate care for medical issues that cis women typically have.

It doesn't mean that there isn't any other possible way, but if you want to understand why there might be some opposition, you first have to acknowledge what the benefits of the existing system have been.