I think it's a relevant discussion. It would be nice to see what could come of it now.
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FWIW, I'm working on book 1 of a trilogy. At the moment, my cast is roughly 50/50. Most of the main characters couldn't alter gender without massive changes to the story. For example, two of the main characters are twin sisters and their lives now had to be redefined by themselves in opposition to their cultic upbringing. They were facing arranged marriages to older men and having to have children. After over a decade away from the cult, circumstances force them back into proximity with it. One of the sisters falls into a relationship with a younger girl who had also fled the cult. The younger girl went through experiences within the society that the twins avoided by running away before being forced to marry. The religious society is adamantly opposed to same-sex relationships - and yet not strictly for religious reasons. There is a more sinister undercurrent. But on the surface, everyone experiences or condones it simply as religious bigotry.
There are two other main characters who are both male. They need to be male to offer romantic possibilities to the other twin, who is straight.
With most of the supporting cast, I could alter genders at will without changing much. Though there is a toxic alpha male who has to be that way. Overall, I've tried to balance the cast.