Not long after EA transformed Origin into a digital only distributor, several Sims 3 games have been removed from the site. The Sims 3 “Plus” & “Deluxe” Games (Base + Expansions) are no longer available for purchase through Origin. In addition to those games, The Sims Medieval and Pirates & Nobles Expansion has also been removed. (Only the Deluxe Edition remains)
It is not clear if EA has just decided to randomly purge these games from their inventory, or if they have discontinued/retired these titles completely. Back in August of 2013, The Sims 3 Katy Perry packs were officially retired, but I believe that had more to do with contractual agreements than purging.
Although these games can no longer be purchased on Origin.com, they can be found at a variety of retailers. Check your local retailers for availability.