See now something like this doesn't bother me in slightest. I feel like a lot of people get hung up on the idea that the rules must somehow be the physics of the game world, rather than just a means to facilitate play. Why does the pirate lord have a high AC? Because it's more interesting than being able to smear him in one shot because he's not wearing plate. The rules were meant to service the story, not the other way around. If anything it would have been nice if that had extended to the PC's more (i.e. things like their AC were more tied to their concept and dramatic convention than their equipment).
Agreed, for the most part. I notice that when the rules tend to be disregarded for the sake of facilitating play, it happens from behind the screen. Players rarely get to play bare-chested pirates with high AC's by virtue of interesting concept. If a PC runs around with no armor on in D&D, he gets pasted. Why should DM's be the only ones who get license to disregard the rules?