JogsterXL: I'm guessing it was because they are essentially "cheat DLCs".
-Scroll Set / Iron Set:
A "cheat DLC" to get a bunch of scrolls/metal; you can get these just fine by playing through the game.
-Rare Weapons Sets A. B, C:
A "cheat DLC" to get some hard-to-get weapons; all weapons are already in the game, you just need to get them.
The DLC Pack GOG has includes just the new content DLC rather than cheats.
-Where Are They Now? / Ryoma Sakamoto / Shinsengumi Set:
All-new missions, accessories, weapons, clothing, etc.
As far as I know, it was the same case with the Agarest games, in that the DLC is basically paid cheats to get you certain items early without playing through the game and getting them the normal way.
Hmm thanks I didn't know this . I though they cut them from GOG release .