I'm not refering to Ashigaru. 'Peasant warriors' does not necessarily mean Ashigaru. Ashigaru (足軽 - lightfeet) is a military term for a particular infantry class in the context of warfare after the establishment of the samurai class (and their pull in politics, eventually leading to the shogunate), so of course the term samurai predates it. Bushi, however, as a more general term for warrior, peasant or otherwise, predates the term Samurai, appearing before the Soga conflict (then referring to people or families trained for and/or charged with military duties, usually of protection) and most prevalently after the Taiho land reforms where the term tended to describe a generally poor class of near-thugs or hired killers/intimidators rather than the likeness of a "samurai class" or even the soldiers drafted for the Kyushu garrison. 'Samurai' as a term came into prevalence only into the decline in Fujiwara power and further divisioning of regional loyalties or especially the 1158 Insei (where the Bushi class, especially via the Minamoto, Taira, and a separate Fujiwara family replaced the former Fujiwara influence) and 1180-5 Genpei (combined on-readings of Minamoto and Taira) conflicts.
Moot point though and I apologize for drawing out this tangent.
I'm not sure how effective stances would be as a gameplay mechanic when the entire point is to never be stuck in any one. They're basically end points for otherwise constant transitional movement. Unless each move variably ended at a certain different stance, and then that gap time between GCDs was somehow important, I just don't see how stances could really be applied. To stay in a stance is to never swing, or else to attempt to beat something to death with repeated, identical half-motion strikes, and even then that would only be because the midpoint (such that you could swing without leaving the stance officially) between those stances wasn't useful enough to get its own name.
I am all for SAM's only real party utility being whatever they, personally, can bring to the fight, though. That or something with a large enough variety rather than just Goad/Rezing/Binding, etc., but that would likewise follow Auron - Power Break, etc.
Here's hoping.