I suppose the author ran out of cash and want to print some more. He has a cash cow at his fingertip. It'd be a damn shame to let this just end I guess?
I've lost all respect for him and the Dragon Ball franchise. You can basically just guess how the story is gonna develop. Stronger enemies come around; protagonists defeated; protagonists train; enemies defeated; rinse and repeat. There's no resemblance of a story, much less a compelling one, in Dragon Ball.