Pauldrons
In the grim darkness of the far future/Renaissance Europe, there is only war. Unless you have Imperial Power Armor/Chaos Plate or Norscan Marauder's hide armor, in which case there is also pauldrons. Pauldrons are the sections of armor that cover the shoulders, and are well known for the tendency of artists drawing Warhammer 40k material to make them ridiculously huge. World of Warcraft armor also tends towards oversized shoulder-plates. (Fuck you, Blizzard!)
In the far far future... Manliness is measured in the size of your pauldrons. Instead of your dick (although that may also count, considering Big E himself was a huge dick).
It is theorized that position in Imperial society is directly related to how large your pauldrons are, as exemplified by artwork of the Empra himself, who has power armor with pauldrons so massive he cannot see over his own shoulders or raise his arms to more than a forty-five degree angle.(Imperial Power armor bypasses this inhibition by having their pauldrons being automated. Thus when an Astartes must look over his shoulders, the pauldrons will automatically lower. As for moving their limbs fluidly, one must keep in mind that the average Space Marines has tremendous physical strength, and thus would be capable of lifting his arms fluidly despite the weight of the armor.)
Those unfortunate enough not to be equipped with power armor instead use the size of their hats in a similar manner.
Privateer Press has copied the style of the huge pauldrons of Warhammer 40k and added comically large pauldrons to some of the characters in its Warmachine game, mostly in the Khadorian army (the Russian badasses). This is most pronounced with Vlad Tzipesci, aka "Lord No-Peripheral-Vision", to the extent that the pads on Vlad's third incarnation are probably a massive troll. A few other models, like the Great Bears of Gallowswood, are certainly not innocent either.
Summarised In a Chaosy Fashion
Our enemy wears METAL BAWKSES, DA COWARDS, DA FUHLES! we... weeee shall wear bigger metal bawkses...
Summarised In an Orky Fashion
'ERE BOSS, YOO WAN GET US SUM OF DEM SHINEY PLATES?
The Truth
The real, secret reason that Imperial society features such massive pauldrons is so that Games Workshop can claim that their armour is distinctive enough to justify suing the pants off any rivals/imitators/wellmeaning fans who produce anything that could be used with their products. Seriously, check this link out: http://www.courthousenews.com/2012/12/04/52810.htm
