Characters could also get their armours bloody after fights, if they were in the front line spilling the blood of the enemies (or losing some of their own). They get their boots and trousers muddy if they walked through mud.
Swen mentioned once that they are developing a system for grit and grime. So that's coming, just isn't ready yet.
But ... I'd much rather they improve the gaming parts before they improve the video parts.
Sure, but it's done by different teams. Not that I'm saying casual clothing must be priority for artists, but artists won't do much about gameplay mechanics.