At first, the blob was named Popopo. It was then renamed Kirby. Did you know Kirby has the same name as the famous Kirby vacuum brand? And that he also has the same name as the famous John Kirby?
As the original (not Gamecube version) Kirby's Air Ride was being developed, the release dates kept on going farther and farther, until POOF. It was cancelled. No one ever came up with a real reason why.
As rumor spread that a new Kirby platformer game for N64 was being developed, word spread that Mr. Sakurai would not participate. In fact, he said so himself he would not get involved. When the game was released, it was then he even bothered to look at the game.
As time passed, later reports gave evidence that Sakurai was clearly losing interest for the later games.
Sakurai quit in June 2003. He claimed to not have hard feelings, but there seemed to be resentment toward the direction of gaming.
Cited from Kirby's Rainbow Resort