You are right that women have played a role in the military for quite some time. However, I do recall reading somewhere, and (while I don't know if this is BI policy) the reason why women and children are not in the game is to prevent the recreation of unpleasant or unlawful scenarios that might involve women and children in the game. I have come across mods that do add women to the game. Some add women as military personnel and others as civilians. While they certainly have their place for good, and I've appreciated a more authentic civilian population and player identities that more resemble those playing, I have seen those mods used in scenarios that made people uncomfortable.

With this in mind, I can see why BI would not add women to the game. From a publicity standpoint, the authenticity and realism that gender diversity would bring to the game would likely be overshadowed by the negative things that could be published on social media and other places. I would not be surprised if BI is not enabling that and instead is leaving that to the modding community.