Looks like Shigeru Miyamoto has a very important contribution to the development of Paper Mario: Sticker Star - convincing the development team to make the story only a minimal part of the game. This is an excerpt from Iwata Asks:
Iwata: Miyamoto-san really persevered with Paper Mario this time. Exactly what was he particular about?And yes, I've been gone for a while and was focused on my other blog. Let's see what'll happen to N-Handhelds from this day and forward.
Tanabe: Aside from wanting us to change the atmosphere a lot, there were two main things that Miyamoto-san said from the start of the project-"It's fine without a story, so do we really need one?" and "As much as possible, complete it with only characters from the Super Mario world.
Iwata: That's a difficult task. In some ways that would be the exact opposite direction from recent games in the series.