It seems understandable that a woman living under the patriarchy would long for a girl. For some, it can be a lonely experience being the only female in a family.
I can understand that feeling of loneliness but not how you'd get from that, acknowledging we suffer under patriarchy, and actively wanting a girl child to come along and accompany you in your suffering? Or am I misinterpreting you, sorry. I am sure that's not what you mean, so I think I am. I'm quite a black and white thinker so sorry if I'm getting that wrong.
I would not call this gender disappointment but I was actually scared about having a girl. CsA and rape in my childhood and teen years, a stalker father, as well as general everyday sexism as it's called. It kept me up at night, worrying about this little girl wandering through life alone and having to face all that stuff. I cried a lot with worry, I think I was mentally unwell so it probably all sounds irrational the amount it affected me. I didn't long for a boy or desperately not want a girl, but I had so much anxiety over the thought of having a girl and her potential suffering that I regretted ever getting pregnant. I did have a girl as it turned out, and Ive since realised she has the kind of parents who will look after her the best they can and not leave her to face everything alone, and I've calmed down.
I've also seen in my dp's family - he is one of five. Four boys, then the youngest child is the girl. Obviously what his parents wanted all along, she has always been treated as the favourite and now all of them have DC of their own, her DC are the favourite grandchildren. If any of them say anything they're told it's because dd's have a special bond... And in this case it's very true, but it was a self fulfilling prophecy because of how they treated her and how they treated their sons.
Their second to youngest child, the youngest son, really hates his sister. I actually find it disturbing how much he hates her. I think it's because he knows how much they wanted a girl, and maybe feels it harder than the others as he's the youngest son. It doesn't excuse how he treats her, it's not her fault that her parents have done this.
It's also been detrimental to her IMO, as I think she is going to find it a real struggle when their parents die - I mean I know most people find it a struggle, but she hasn't been given the opportunity to be fully independent and I think on a practical level she will find life hard.
I'm sure for the majority of parents they'd not treat their kids so differently like that, but I think either consciously as with dp's parents, and subconsciously for some others, it does happen and it can be damaging.