The hat wasn't made by Maxis. It was a community collaboration with one of the popular CC creators and was CC originally. I forget who the creator was atm, but they were in one of the livestreams a year or two ago where it debuted. There are a number of CAS and a few build/buy items that have been brought into the game that way. Several CC creators have had their creations added to the game for everyone to enjoy over the last few years. There's a pair of jeans, a robe, the durag, some table and chairs, a side table a few more things over time. They are marked in CAS with a little green flag though so you can look in your game and find them. Matter of fact, there are 2 hair styles coming soon (as in this week) that are community member creations. I think it's great that Maxis is doing this and would like to see more items added this way.
Hope this helps
