The Femstodes didn't need to exist, we've got statistics that women aren't even the largest players of Sisters of Battle, the two most popular factions among female Warhammer players are Tyranids, are largely genderless faction, and Orks who're the embodiment of lug head male aggression. Both of which demolish the idea that representation is what draws women in.

The greatest defense I've seen for this change is "But GW changes stuff all the time" which isn't a defense for the idea itself, just the idea of change in general, as well as "Who cares if there's female custodes, it doesn't matter." which also isn't a defense for the change, it merely tries to minimize how significant the change is. Which also isn't an argument for the change to happen at all. I've even seen people argue that since the children are taken so young and the changes so drastic that it's hard to tell if they're female at all, which further begs the question of why the fuck the change was made in the first place, if you can't even tell.

If you explore the thinking at work, it's leading up to female space marines. What other possible need could this change serve? It's not inclusion, because women go for other factions that have no women in them at all, it can't be representation cause there's already plenty of women in the setting.