However, buyers quickly noticed that the download itself was extremely small--23KB on PC, 108KB on Xbox 360 and 103KB on PlayStation 3--suggesting that the download wasn't adding new content, but rather unlocking content already on the game disc.
That suspicion was quickly addressed by 2K Games, which explained that this was done to avoid splitting the player base--if the data needed to support the multiplayer tweaks wasn't available to everyone, then those who hadn't purchased it wouldn't be able to properly play against those who had bought the extra characters and upgrades:
The way our engine and game structure works is that people need to have the exact same content for people to play together. One of the challenges with post launch content for MP is that it can split the player base, and we want to avoid that whenever possible. For this content, creating the DLC package the way we did allowed for us to not split the player base - so whether you purchase the new content or not, you can still play with your friends.
I know some of you have strong beliefs about DLC, and I'm not here to sway your opinion or convince you to buy our stuff - if you like what we're offering, I hope you get it and enjoy it. If it's not your speed, enjoy BioShock 2 as we released it.
I want to let you know that DLC is not interfering with our patching capabilities, which are a top priority and are still being actively worked on. We're committed to supporting you and making BioShock 2 the best experience possible.
Of course, that doesn't answer the core question of "if it's already on the disc, why not make it available to everyone from the get-go"--a possible but entirely theoretical answer to which could involve the content being made under the downloadable content budget, and thus requiring the additional fee to break even and/or turn a profit.
As noted above, this particular add-on ("Sinclair Solutions Tester Pack") is only the first in 2K's "aggressive" plans. It remains to be see whether the additional single-player and multiplayer content due across the coming months is already on the disc as well.