How did the development of writing change the societies of ancient Mesopotamia and, specifically, the lives of their people?

The development of writing allowed the memorization of laws, business transactions, records of account, including taxes, etc. It demonstrated the superiority of the written word over oral memory which can be faulty, or perhaps deliberately misstated. It was not by coincidence that the first writing was done on clay tablets which hardened, and it was thereby "written in stone," and could not be changed. It was there for all to see.