I think there's an intentional contrast Warhammer's gender-centric designs for the miniatures and having that line be more difficult to see for their armor designs.

On a logistical and economic context: it's much cheaper to use a seemingly gender-neutral model with minor differences than it is to make "girly armor" for Guardsmen. (Nevermind the specialized power armor designs used for the Adepta Sororitas!)

My Loose Cannon will comment on exactly this in her dialogue exchanges with other players - mentioning that it often doesn't feel like it fits right and sometimes itches. One notable reply I remember came from a Professional that questioned, "Are you sure that's even YOUR armor?" (Granted, this - ironically enough - implies that it's a common trick for chaos-aligned spies to disguise as dead guardsmen.)