Fun fact: Traditional partners were planned to be included in Paper Mario for 3DS, but Miyamoto rejected the idea because he “wanted us to make a big change in the atmosphere for Paper Mario this time.” (Iwata Asks)

So for the sake of having something completely different and not retreading old ground, Miyamoto rejected a potential Paper Mario RPG for the 3DS. He also said that when he played the prototype which featured partners, he was disappointed that it “felt like a port of Thousand Year Door.”