Hideo Kojima has said that he originally planned to step back a bit from future releases of Metal Gear and wear the hat of producer.
Instead, according to an interview in Dengeki: PlayStation, he admits that the story in Metal Gear Solid: Peace Walker was too complex for him to not have a hand in.
“At first, I was just going to create the overall guidelines and concepts for the project, and leave it in the hands my excellent staff," he said. "I was going to have a hand in the project as a producer, and make titles other than MGS.
"But, I set the game in the South American(sic) country of Costa Rica and created a story with themes about nuclear deterrence and the cold war. It looked as if it might be very confusing to young people, because of generational differences. So, in the end I finally said, “I’ll do it.”
Kojima also revealed that Metal Gear Solid: Rising will not be a "traditional" Metal Gear game as the action will be much different than what has appeared in the series so far.