It attracts the Conan crowd. It's also a good way of showing off the Dragon shouts magical protection effects.
We really don't see any indication that magical protection was involved in the fight, though. I mean, sure, the Dragonborn survives getting a dragon's fire breath to the face, but at least if it's anything like past games, you'd really just need a lot of health to survive that, and I'm sure that in the trailer, Bethesda enabled godmode to prevent shots from being ruined by the unintended deaths of the player character. Really, I think that the reason why they'd wear only one pauldron, assuming this was a conscious choice made in the game and not just the way the armor is designed, is simply because they thought it would look cool.