Think about it. Jarod is a character created in the novels, who doesn't appear in any other source. In the end of the novels, Jarod is the leader of the Kaldorei. He's a hero who faced Archimonde himself, and several battles were won thanks to his strategies. Everybody, including the other races, liked him. Maybe Knaak felt attached to his character, or maybe he didn't want to end the books on a low note. At least, that's the impression I got when I read the novels.