The game prints enough money that they could afford to have a writing staff and illustration team. I think the idea is that building character depth will make a subset of players more connected to them. This keeps them playing and also increases the odds of them buying a skin for the character.
It's similar to the Meet The ______ videos from TF2 and the comics that built on them.
It doesn't allow for any use of your data. It allows for use of your data to do the things you ask it to do. That permission is implied by you asking it to do something, but it isn't explicitly stated.
The AI clause is conditional. It only applies if you use the AI features.