The reading talks about the rules of Material Design UIs. By giving all the rules of Material Design, the designers' goal is to make people use and understand users' interface more easily. Good designers create user interface when they stand on people's positions; they think about what is the best for users.
I wonder what if the material's shape is too irregular, will people still feel comfortable to view content in the material. Or does the material shape have to be geometrical to make people to feel comfortable..?