My husband was just telling me this same thing yesterday, that he'd love a "Search by Gathering" option.

Of course if it was even smarter to search for both and show whichever was relevant would be nice too.
Or if they completely revamped the search feature to use a database (lodestone database maybe?) to show more methods. There are some gatherable/craftable items that can also be bought from NPCs, others that are dropped by monsters/instance rewards, etc..

But starting with just a quick way to search though the gathering log would definitely be a good start!