Oh well, lets keep this charade going.

Onion farming is a complementary addition to the rest of the crops. You plant, harvest and make food from the harvested onions. It's a decent system and onions add a bit of variety.
Is onion farming, in particular, more fun than farming any other crops? Not really. It's just additional content to an EA game. Is the game improved by having more content and greater variety? Yes, it is.