You don't, but lots of people from other countries do because of the tax structure in their countries.I don't go to Disney's mall to buy French milled lavender soap, designer sunglasses and silk ascots. I want Orange Bird juice glasses, EPCOT Center t-shirts and reproductions of Mary Blair prints. DH wants pins. And the kids want Prince Philip and Beast foam swords and shields to beat the snot out of each other....
Even though I would never buy 99.9% at Disney Springs I get what they were going for and think they did a fine job. There is a massive assortment of "Disney" merch between Marketplace and West Side (World of Disney itself is enormous) and having even more would just be redundant. The part in the middle was obviously built to keep people away from the Premium Outlets. The way I look at is that they basically tried to make everyone happy, the Disney Fans, the high-end shoppers, and the "foodies" all got what they wanted. They also fixed the huge traffic and parking problems as well.