personaly, i wouldn't call it feminist breakthrough, because this isnt the first game that treat the appirance of woman as man are.
(in most of modern games, womans are as equal to man, really.)

but what really deserve an applaud, is the "normlizetion" of the female charecters.. make them ordinery, not extra cute or pretty. (valve recived alot of good ratings on the making of alex vance, by making her simple "human", yet loveable charecter over the personality behind)