Why should women have agency over a doctor's own practice of medicine, and dictate to him what treatments he may and may not consider ethical?
I mean, it's a really weird question to be asking. We all understand that not every treatment someone could ask for will be healthy or ethical in every case. We all understand that in general, doctors need to be able to exercise their own ethical judgement when it comes to treating prospective patients.
The issue is not whether a woman should be able to command a hysterectomy whenever she wants, overriding her physician's misgivings if necessary. The issue is why we find ourselves now in a society where women often find it more difficult to get hysterectomy for non-trans reasons than for trans reasons.