Cannot speak for or to why much of this is happening but at least for these sort of policy changes put forth by the WH it is part of his vow to make things "eaiser" for LGBT persons without having to go through Congress. This current announcement fits in with previous ones this month such as the DoE removing "Father" and 'Mother" from financial aid form to be replaced by "Parent 1" and "Parent 2". And so it goes.
While some females don't have a problem with men or anyone else in the powder room. quite a few still do and they fit transgender into that category. Far as they are concerned a " man is a man is a man", period.
Know a few transgender RNs. Three went to nursing school during the 1980's and 1990's and none had an easy time of things.
First because they were legally male according to their ID (high school transcripts, birth certificates, etc...) they were informed by those running said programs they would enter and be treated as male nursing students. This meant no visible make-up, nail polish etc.. and they had to wear the uniform
assigned to their gender. The last bit created no end of problems as they all had begun hormonal treatments and had feminine figures including a bust. This became visually obvious under the standard "Dr. Kildaire" tunics the programs used for male student nurse's uniforms.
At clinical sites they were told under no circumstances could they use the facilities designated for females. If the nurse's restrooms were unisex, fine; however if as with many older hospitals the female nurse's restrooms on the floors were part of the locker room, it was out of bounds.
Final insult came at graduation/capping and pinning. None were allowed to attend in female attire and were told to wear whatever was required for male nursing grads. They weren't even allowed to order caps (why do you want one? male nurses don't wear them) as the women were. Happily some either got theirs from sympathetic cohorts or went out and got them from Kay's or elsewhere afterwards.