if it's just about the way they talk, then they're going to talk that way because it's easier for us to understand it, and it's what the writer knows
how are these women acting like they're from the 21st century? what i see are women acting like the men, and as i said, that's to make them more interesting. if they acted like real ladies, they wouldn't do that much. i guess you could say, in some ways cersi and sansa in martin's song of ice and fire act like real ladies. even catelyn did. they stayed home, they had kids (well not sansa, but she was all dainty and pretty and worried about husband and that sort of lady things) but when the world goes into crap, they had to do SOMETHING and play a part, or they'd have ended up dead (well cat did)
i think that's something else to remember. if a woman acts the way tha a woman would have done back then, she'd either have not done very much, OR if the world had gone to war and so on, she'd have died, if she didn't adapt. it just isn't practical for women to sit around and be ladies in fantasy. and in honesty, i'd find it boring and offensive. to me it's bad enough that there are very few strong female characters who aren't whiney or self invovled, i really woudn't want to read about a hoast of them who can't do very much.
and i dont' actually thinkg women have ever been 'ladies.' they may apepar that way, because of social custom, but it was rarely that way. even the ancient greek women, who were so protected they weren't really allowed out on their own, who had kids and weren't wanted for much else, ran their husband's household.
so yeah, it really depends wht you're talking about. if it's the way that they speak, well the men also speak like they're from this century. if it's the way that they act, well they have to act that way, if they didn't they'd end up dead or left behind. you wouldn't take a dainity princess on a quest with you. if the women were like the sterotyped idea of ladies, they'd not be in the book. if they were like the real way that women, percieved as ladies, behaved, well that is how they're potrayed. as women who will fight back when they need to, stand their ground when they have to, and so on.