Answer! Both were initially developed with completely new characters in mind before Nintendo franchise characters took over in the end.
You see, Epic Yarn was originally going to be a game with a completely original character:
One of the big revelations from the [latest Iwata Asks column] is that Kirby’s Epic Yarn originally wasn’t a Kirby game. Good Feel developed the game with the desire to try something new, and so they started from zero. The Japanese name for Kirby’s Epic Yarn is Keito no Kirby, or Kirby’s Yarn. Instead of this, the game was originally set to be called Keito no Fluff, or Fluff’s Yarn and would have starred a character named Fluff in a world known as “World of Yarn.”
I’m all for new characters, especially from a company as franchise-heavy as Nintendo, but for some reason I’m content knowing Kirby will be the character that’s going to shepherd this surprising, lush-looking title into the world.
Cool trivia: Developers at Feel Good were given yarn and fabric to touch while developing this game.