Regardless of their guilt, a president's Executive Privilege can prove to be advantageous if used correctly. During the Mueller Investigation, President Donald Trump used his Executive Privilege against Robert Mueller

As Commander in Chief, POTUS can deploy troops, only needing a Declaration of War after 90 days of deployment.

POTUS has veto power. This means that POTUS has the option to sign a bill or even flat out refuse said bill

Article II of the Constitution states that the President of the United States is also referred to as Commander in Chief. Commander in Chief isn't just an honorary title either, POTUS is the head of all branches of our standing Military (US Marine Corps, US Army, US Navy, US Air Force, and the Coast Guard)

The president can use Executive Privilege to keep their presidential duties behind closed doors. Executive Privilege can and has been used effectively by several US presidents including George Washington, Barack Obama, and the current POTUS, Donald Trump

The Constitution already does this, so is a Bill of Rights even necessary?

A central government is needed to regulate and control laws. The states alone shouldn't have the power to pass laws, but actual individuals were instead needed.

The Federalists stated that federal courts were necessary as a mediator on state issues and so forth. Centralization was required for a good, well-functioning government.

The Federalists saw the addition of the Bill of Rights to the Constitution as unnecessary. The Federalists believed that our Constitution was a fine and proper addition to the Declaration of Independence and a Bill of Rights was pointless as the Constitution was simply, just that, enough. This was the common Federalist mindset.