Mods from Ada-1 are built around how mods worked before New Light was released. They were designed to be consumable, so you need as many as you could get to satisfy your needs. With New Light (and by extension, Shadowkeep), mods are now unlocks that you can reuse. Bungie may have left her Ada this way to provide a way to use your Mod Components. At present, you'll need to continue to give her materials until you have unlocked all her mods. Be careful about trying to get too many in a single day, however. The price goes up for each one, but resets the following day.