A lot of people have been asking about the 12 additional characters for Street Fighter X Tekken and why they aren't available for download (or unlock). Rumors spurred that Capcom is in a legal bind to keep the characters locked until the release of the PS Vita version.
Allegedly, Capcom went to Sony and Microsoft for exclusive content for each version of Street Fighter X Tekken. Sony was willing to pony up some money and pay for additional characters, as reported by CVG, however Microsoft was not feeling it and declined to have first-party characters appear in Street Fighter X Tekken. In result, Sony went the extra step to not only secure exclusive characters for their version of Street Fighter X Tekken (i.e., Kuro, Toro, Cole, Megaman and Pac-Man) but allegedly also paid Capcom for 12 additional timed-exclusive characters for the PS Vita version of the game, which is due out this fall. Purportedly, the characters are not to be made accessible on the home consoles until the PS Vita version releases in order to help boost the appeal of Sony's new handheld.
Those 12 additional characters are also available on the Xbox 360 and PS3 versions of the game and are, without a shadow of a doubt, as complete as the other pugilists on the roster. Some gamers were hoping that Capcom would release these characters over a course of time for a fixed priced as suggested by GiantBomb, instead Capcom announced that all 12 characters would be available for $20 alongside the release of the PS Vita version of the game, as reported by Venture Beat.
The reason for this is that the hackers have revealed that the 12 characters locked behind the pay wall on the discs are behind a very simple "hex wall". According to the hackers the characters were easily accessible using a very simple numerical hex switch which activates all 12 characters, enabling them to appear on the main roster. When the switch is flipped the other way (using '1' and '0' as the on and off switch respectively) the characters are locked. Accordingly, the hackers have stated that it is not possible to only activate some of the 12 characters from behind the hex wall. All of them must be activated at the same time or none at all.
The hackers discussed that this "hex wall" could potentially be patched to separate the characters into individual or paired downloads but as Capcom revealed, all 12 characters will be accessible for the flat rate of $20.
Additionally, the hackers revealed that the characters are also interchangeable from behind the "hex wall", which they showcased in their ranked Xbox Live matches, meaning that characters could be moved from behind the wall or put behind the wall by interchanging roster slots. As some individuals speculated already, the 12 locked fan-favorite characters could have been arbitrarily chosen and it very well could have been any of the 38 (or 43 in the case of the PS3) characters locked behind the wall.
As noted by the hackers, the wall itself was a very flimsy safeguard to protect the characters, meaning that it was either a last minute addition or Capcom just didn't care. Theoretically it would make sense that the wall was a last minute addition and the 12 disc-locked characters potentially could have been unlocked by actually playing the game. This was usually the case with previous fighting games, including Marvel Vs Capcom 2, Tekken 6 or Mortal Kombat, to name a few.
However, if Sony wanted extra content for the PS Vita version, it would make sense for Capcom to simply lock away completed characters as opposed to spending extra time and resources (which they claimed they did not have to implement pair-play for the Xbox 360) to build 12 brand new characters to release this fall.
From this perspective it doesn't appear that the characters were ever intended to be included on the disc for compatibility purposes but instead were simply removed from the main roster and placed behind the hex wall. As proven with indie titles like Dungeon Defenders or other fighting games like BlazBlue or King of Fighters, you don't have to finish DLC before a game goes gold for the multiplayer DLC to be compatible.
Capcom has already begun rolling out some of the DLC, including the first pack of 12 free colors, Gems and the first set of the Swap costumes. The Cosplay costumes will arrive later along with additional color packs. As mentioned, the 12 disc-locked characters won't become available until after the release of the PS Vita version of Street Fighter X Tekken this fall.