DLC Codes have universal appeal. Regardless of other interests like figurines or plushies, anyone playing Neptune can make use of DLC Codes. Unless NISA wants to hear DO NOT WANT from gamers who're buying the game for the game alone rather than the random goodies, making the bundle bonus DLC codes is a matter of course. Providing the extra content is actually worth the extra price. Also, a soundtrack couldn't hurt. But rips of the game music will probably wind up online anyway thus resulting in a pointlessly inflated price tag. So yeah, the only practical choice that appeals to the greatest number of gamers is DLC codes.
But then again, this is a game about the consoles gamers own turning into little girls. Cue the unfortunate implications and appeal's probably not on NISA's list of things to give two shits about. In that case, it probably doesn't really matter what they have in the bundle.
Lowering the price of the PS3 to $150 is like mass producing the Big Zam. It's the greatest idea that will never come to pass. OH SHI-!