Because they had to re-write it...
You can either drip feed a book chapter by chapter, or you can release the completed novel.
I love the way people seem to think Stef is delaying things for the giggle. Bearing in mind the quicker he releases the update and the more often he updates it, the quicker he makes money and the more money he makes from it.
I also love how people seem to think that 1.5 is going to be a completely new game or be the answer to all their problems. Spoiler alert. It's going to be exactly the same game.
Infact, it's going to get a lot harder for most users because the drag bug will be fixed and 80% of players have no idea that it even exists.