A difference of return philosophy might account for the differences in stance.
Women often return much more aggresively, since the serve isn't nearly as fast, so they need a stable hitting platform.
Men serve much faster, and most big servers target the body to freeze the returner from reacting out wide. So it's a more defensive return of serve in men's tennis.
Wide stance allows a quicker wide movement, and allows the returner to pivot off one leg and defend body shots with turned shoulders.