If you're looking to build a backstory, then the categorizations and fluff actually detract from that, not add to it. Example: Why does my character have to be a Vagabond Child or a Kobold's Neighbor to know how to pick locks? Maybe he grew up is a stable, nuclear, well-to-do family of thieves and burglars. If I have a concept for a character like that, the fluff actually prevents me from building what I want.
Look, the fluff for the traits is a useful tool if you have no idea what you want out of a character. If you do know what you want, then it is a straitjacket. Furthermore, they're a crutch for Paizo, who continually recolors the same basic traits over and over again. Here's +1 Reflex as a Combat trait. Here's +1 Reflex as a Race trait. Here's +1 Reflex as a Regional trait. Here's +1 Reflex as a Campaign trait. Whoopee.
Yeah, the streamlined traits can be used more easily by powergamers to get what they want. So what? Powergamers are going pick the traits they want anyway. All this does is save the rest of us from hearing some tortured backstory about how Joe the fighter grew up as a street urchin while training under the world's greatest homeless swordsman, and then inherited his masterwork weapon when the old guy died. At least a non-backstory doesn't challenge my suspension of disbelief.
EDIT: SotS ninja'ed my talking points.