Let's face it: Pigs are terrible.
They have no special drops, unlike the cow, and the ride feature has been beaten by horses.
I propose a solution, to make pigs useful:
Truffles would be a rare drop from pigs, with 2 uses.
1: Can be brewed into a "Fortune Potion", which would strengthen the Fortune enchantment, with Fortune 3 becoming Fortune 5 temporarily.
2: Can be traded to villagers for a large sum of emeralds, depending on the rarity.