The original plan was to use the Super Draco thrusters for a powered landing on ground rather than a parachute-braked landing on water. They would also double up as escape rockets during a launch if things went wrong.
To achieve this they had to put the Super Draco motors and the highly toxic fuel and oxidiser to power them in the capsule structure beside the crew. Existing capsule escape systems use a set of rockets on a tower mounted to the top of the capsule. It's usually jettisoned in a normal flight to reduce weight and free up the docking adapter in the nose of the capsule once the point in the launch where a powered escape isn't going to be successful has been reached.
Now SpaceX has abandoned the powered landing concept they're stuck with lifting the mass of the entire Super Draco system plus fuel and oxidiser to orbit and returning to Earth with it, basically parasitic weight if things go right. It would require a major redesign to remove them from the capsule and add a disposable escape tower system like the Boeing capsule has.