If the 'why' behind the game's loyal reprise is Platinum's interest in Korra, the 'how' is their tight collaboration with the series' creators. The game's script is the work of Tim Hedrick, writer for both The Last Airbender ("The Puppetmaster") and Legend of Korra ("Beginnings, Part 2"), meaning the tale we're getting comes right from the source. The game also sports the same voice actors as the show, as well as the same background music and even sound effects. Then there's the final boss, and while his/her/its identity remains a mystery, we know that creators from Nickelodeon Animation and Platinum directly collaborated on its design, ensuring it fits within the story we know and love.
Since the show's current fans are this game's biggest market, this kind of exchange is a definite plus. In a perfect world, all tie-in games would get this kind of treatment, with assets liberally shared between studios. This seems to be the exception however, and it's exciting to see creators and devs working together to build a product worthy of Korra's wide fanbase.