Nintendo recently launched Chibi-Robo! Zip Lash on 3DS, and many fans are concerned that it could be the last game in the franchise due to mixed reviews and underwhelming early sales. Chibi-Robo! has used a 3D adventure style in the past, but Zip Lash features a simpler 2D side-scrolling style instead.
Assistant producer Risa Tabata has previously said that she'd like to return to the 3D style in the future, but that would be more expensive, so Zip Lash needs to perform well for that to happen. Tabata brought up another obstacle to a 3D Chibi-Robo! game in a recent interview, stating that the reason Zip Lash is 2D is that a 3D game would be too hard for children, and Nintendo doesn't want to make Chibi-Robo! inaccessible to young gamers.
"A 3D landscape would allow you to do more, but would also make controls and aiming more complex and the game harder overall. Chibi-Robo is a character who’s beloved by a lot of small children as well, so I wanted this game to be accessible to that audience too." — Risa Tabata
Chibi-Robo!'s established audience is a very small niche, and the first game launched over a decade ago in Japan, but children apparently make up a large enough portion of the audience that Tabata felt a 3D game wouldn't work at this time. Unfortunately, given Zip Lash's poor start, it's looking more and more likely that we won't see another entry in the franchise.
Source: US Gamer