This question is highly dependent on personal beliefs; however, a lot of people will come to a standpoint that the Bill of Rights was indeed a necessary addition to the US Constitution.
While the Constitution served as a blueprint and foundation for the national government, citizens were worried that the document itself never established or accounted for individual rights. After many years of debate and argument, the Bill of Rights was ratified in the Constitution to address the physical inalienable rights humans have within the country. Some of these rights include freedom of speech, freedom of the press, and the right to bear arms (as in weapons).
To assure a system of permanent and unaltered rights, the Bill of Rights was established. This way, everyone could enjoy their own liberties under due process of the law.