The Founders of the nation gave us the Bill of Rights because they did not trust the federal government sufficiently to allow it to function without a Bill of Rights. The people who wrote the Constitution were happy enough to leave out these enumerations of rights, but they were forced to include the Bill of Rights by critics who did not trust the federal government.
At the time of the Revolution, one of the main complaints about the British government was that it did not respect the rights of the American colonists. When the war was over, the Americans did not want to create a government that could trample their rights the way the British had. Therefore, they created a very weak central government. They trusted the state governments, not the federal government.
At the Constitutional Convention in 1787, a stronger federal government was created. Because the federal government was going to be strong, it could also be seen as a danger to people’s rights. Therefore, many people wanted the Constitution to include specific limitations on what government could do so that it would not harm people’s rights. It was because of these fears that the Bill of Rights was added to the Constitution.