For the pros of no formal identification is you can design your identification by yourself. The form of each identification will be more beautiful more cute. So you can hide your information that you do not want other people know that details and you can fill other of your information to let other people know such as favorite food, your habit.
For the cons of no formal identification is the security hardly to investigate. Because of each of them that have many different form and different color. But the important is there will have people who want to escape out of theirs country.