As I noted in another thread, people who are using the lore as if it were "the justification" for the decision are misguided, and that was never the point of any comment made by the dev team. There is and will be an in-lore "rationalization" for their decision, because obviously there will be. But if they decide later on to flesh out the other genders for the respective races, there will be an in-lore rationalization for that as well. This is just a development decision on how to allocate costs and resources internally, and prioritization based on marketing, leadership preference, or whatever other factors entered their decision-making. They're definitely not bound or restricted in any way by the lore, and could easily add the other genders later if they think it's worth doing. (If people keep the pressure up over the long term, it'll support that it's worth doing.)