Masks are a staple of superhero costumes, but hey, guess what? The Winter Soldier’s is depressing as hell, just like every other aspect of his life.
While Steve’s “mask” is more like a helmet than anything else (particularly since he no longer has a secret identity to protect), the Winter Soldier’s mask is basically a muzzle. Not only does it anonymize with him far more efficiency than the domino mask we often see him wearing in the comics, but it dehumanizes him, showing only a few slivers of visible skin to indicate that he’s anything other than a relentless cyborg. With the goggles on he’s almost completely faceless, and the muzzle serves to hide Sebastian Stan’s expressive mouth. And although he does bark out a few orders during one of the fight scenes, that mask is not exactly conducive to friendly conversation — possibly a subtle callback to the facial restraint we see Loki wearing at the end of Avengers. Not pleasant in the slightest.
— Costuming and design in Captain America: The Winter Soldier.