freelancer_bob (love that name) over on LJ has a good point: Shoulderpads seem to be the height of fashion in Azeroth. Not only do shoulder pieces call for the highest Arena rating in the game, but they're often the flashiest way to add a little flair to your character. While you can get the plainest of the plain before level 20, after level 70, they quickly and often turn into the wackiest thing your character can wear. Whether it's pure energy, lightning wolves, or even eyes (freakin' eyes!), Blizzard's artists seem to go overboard as much as possible, especially on the high end shoulder pieces.
Sometimes it just gets out of hand -- how exactly are Hunters wearing Tier 1 supposed to use their peripheral vision? But just as Bob says, oversized and garish shoulders are a big part of what makes WoW Warcraft. If we walked around with realistic shoulder armor, the game would look that much more boring.
So here's to the praises of huge, awesome-looking shoulders. We're looking forward to a lot of stuff in Wrath of the Lich King -- the new class, the dungeons, and the new continent to wander around on. But I'm also looking forward to seeing just how the armor designers will top having blindfolded statues of women on shoulder pieces. It'll be amazing for sure.