Merchandising used to be an afterthought, just ugly band t-shirts with logos and concert dates printed on the back.
But nowadays, it is turning into a legitimate business: artists are partnering with streetwear celebs to create merchandising that has value in and of itself. While it may not be a traditional luxury product, it is part of the new luxury economy (see Taste is the new wealth).
This is similar to what A24 is doing with its merchandising shop.