They were not reworked in Gen 3, but in Gen 4.
They were reworked in Gen 4 because it was about that time, that Gamefreak had started to somewhat revamp the whole attackdex.
Like the thing that all the Dark type moves were special, but comprised of moves like Bite, Crunch ane Thief. As of such, we don't really know their original intentions, but this is the most likely theory.
Hope I helped!