The advantages of an outboard motor bracket:
Less draft - The bracket adds additional displacement (floatation) which helps to support the weight of the outboard motors. The outboards can also be mounted higher on the bracket than if it was mounted directly on the transom, reducing drag.
More cockpit space - Without the motors hanging on the transom there's no rigging or motor cowling encroaching into the cockpit. No motor well and no need for a secondary transom bulkhead.
Better performance - You have the cockpit room of a much larger hull with the lighter weight and less wetted surface of a smaller hull. The higher outboard mounting position and decreased drag makes the boat easier for the outboards to push. This equals faster speeds and more fuel efficiency.
Safety - The full heighth transom gives you peace of mind with reduced possibility of water coming over the stern, even when backing down in heavy seas.
Less noise - With the outboard motors further away from the helm and separated by the transom, it's quieter.
Protection - Outboards trim completely out of the water.
Better water access - A ladder mounted to the bracket lets you use the bracket like a swim platform.