The folks at Gearbox have put up an article—an in-depth feature with Borderlands 2 writer Anthony Burch on the contradictions in writing on Borderlands 2.
The first article, titled "Inside the Box: Fart Jokes and Tragedy", goes into no small amount of depth about the upcoming expansion pack, Tiny Tina's Assault on Dragon Keep, which is coming out on June 25. The article addresses the issue of Borderlands' tone.
"Tiny Tina’s Assault on Dragon Keep is about a group of friends – Tina, Brick, Lilith, and Mordecai – playing a tabletop roleplaying game. As the player, you fight through Tina’s fantasy module as it exists in her imagination – this means that you get to fight orcs, skeletons, dwarves, and all other kinds of fantasy-centric stuff that wouldn’t make sense in the universe of Pandora. It also means that your explicit goal in the plot is relatively simple (and in honesty, sort of cliché): you’ve got to track down the evil Handsome Sorcerer who brought darkness to the land, and rescue the beautiful Queen of Flamerock Refuge from his evil clutches."
As for writing about the game itself, Burch writes:
Instead, we try to keep a kind of lopsided balance between humor and tragedy. Anything that gets too goofy should have something to give it a little bit of darkness and weight. For instance, the "You Are Cordially Invited" mission in Borderlands 2: it’s pure Alice in Wonderland wackiness for the most part, tasking you with killing bandits to protect a “tea party” where Tiny Tina tortures an evil bandit named Fleshstick for kicks. It’s over-the-top and, while violent, played pretty much for laughs. That is, until you find out why Tina is torturing Fleshstick: he sold Tina’s parents out to Hyperion, and she had to watch them get tortured to death in front of her (which subsequently shattered her mind and turned her into the person she is now).
Elsewhere on the internet, DLCentral has a Q&A with both Burch and Paul Hellquist about the game itself.