One of my major complaints with Paper Mario: Sticker Star was that the game, unlike its predecessors, lacked a compelling story. In a recent Iwata Asks session, the developers behind Paper Mario have shed some light on the storyline issues. In a segment titled “Abandoning the RPG Structure,” Taro Kudo and Kensuke Tanabe mention that, though they’d originally intended for there to be a focused narrative, Miyamoto had told them that the game played fine without it. He also asserted that they should try to, almost exclusively, use existing characters from the Super Mario universe.
The lack of a solid narrative, though, made Sticker Star feel aimless--focused purely on its game play. It’s fine if the game play in a title is a huge draw, but Sticker Star also stumbled there, The RPG element of character growth used to be a franchise centerpiece, but it was axed in favor of introducing the player to increasingly powerful stickers. Though this was balanced, it wasn’t fun because battle did little to offer any sense of progression. Tanabe further asserted that the removal of RPG elements, and focus on stickers, was a conscious decision. It goes to show that, sometimes, even the best of minds can make poor choices.
Source: Iwata Asks