http://forum.square-enix.com/ffxiv/t...-and-Additions

Ingredients that may return in a future patch
Ingredients becoming obsolete

IMO I just NPCed them, can't be bothered waiting around for years waiting for an official response. But yu are right, it's a waste of memory but whats worse is some still remain in the game as dungeon drops "Red Megalocrab Shell", "Titan's Heart" that are useless.