LocoRoco creator Tsutomo Kouno is only one man. Ask him, he'll tell you. So, even if he wanted to make all the ideas he has for new games, Kouno couldn't. He tells Games Industry:

I have many ideas, but I can't make them all because I am only one person. I have five or six new game ideas either for PSP or PS3, but I actually want to make them for PSP — for the people who bought LocoRoco, or bought a PSP because of LocoRoco, and like casual games... There are too many sequels for PSP, only sequels, so I want to make a new game for PSP.

Kouno is hard at work on LocoRoco 2 for the PSP. Brian Ashcraft

Loco for Originality [Games Industry]