I think it's great that they are not making BoJack "just the douche" character. Backstories help a lot but it's also just about setting up the scene: can people be good in the environment? What are the motivations, challenges, triggers, and obstacles? Who defines happiness?
You were born broken. That's your birthright. And now you can fill your life with projects, your books and your movies and your little girlfriends, but it won't make you whole. You're BoJack Horseman. There's no cure for that.