Why did Peter Jackson change the whole hobbits around, in the book azog name is only mentioned once in the book par Gandalf, plus azog son bolg becomes ruler after his son dies

My guess was he wanted plus villains with actual identities and personalities than just Smaug at the end. In the book, the orcs are just aléatoire orcs. He probably thought it'd be plus interesting to give them names and backstories, so he took stuff from the appendices of Lord Of The Rings. And he probably kept the father orc alive to get another villain.