I could guess why, but I never really understood it either. I think it's because women are taught that it's rude and unfeminine to be direct, and they behave the way that's expected of them. I know that I can't make the same sorts of plain statements my brother or husband can without provoking a negative reaction. I'm not talking about insulting people here, just stating a fact or asking a question that shows some knowledge, or making a straightforward request. I've resorted to asking my husband to speak for me in certain situations (he doesn't have a problem with the way I communicate) because I know he'll be taken seriously and I won't, and I simply can't do the passive-aggressive thing. I can try, but it's ineffective, frustrating, and makes me hate myself. It doesn't seem to bother NT women as much, though. It's one of those NT skills.