I think the bulky bit is just to impress the male body type -- for the longest time, fantasy warrioress were bikini-clad amazons, they are lucky to get pauldrons, let's the cultural imprints are still there -- inverse triangle upper torso simply looks more impressive. Part of that might have also been the pop-culture fantasy of the American cartoons in the 80s. So the thought process was likely muscle-bound Heman/Conan/what-have-yous gonna wear armour? Bigger torso! Giant pauldrons!
Take Warhammer, for example, their normie humans wore mostly normal armour, though yes, the higher-ups are quite decorated. But the northern barbarian baddies wore armours with pauldrons, when modelled-as-depicted and used in the Warsword Conquest mod, blocks the vision in first person view -- though this also has to do with how games render first person views is different from how we'd see from two eyes.
The one on the left is a normal dude with rich parents and maybe trained alot. The one on the right does 1,000 push-ups every day since birth, in the winter, outside in the snow, and has supernatural strength granted to them by otherworldly dieties.