I agree that it's a delicate balance to tread, and of course mileage may differ, but in this book I think Barker manages to avoid this. Neither Briseis nor anyone else, for example, expects to marry for love pre war, and of course marriage is a decision your family makes for you, based on alliances. Briseis does have something of a wake up call re: slavery once she's a slave herself, but it's not phrased as "all slavery is wrong", but more on the lines of "I wonder whether this is how our slaves felt about us?"