Packaging the mechanical components of a Formula 1 car is never an easy task, especially when you consider that all of its body surfaces are there to influence the airflow and, in most cases, create downforce.
The current breed of F1 car will create something in the region of 1200kg of aerodynamic downforce at 155mph - so it's easy to understand why aerodynamics is a prime factor in packaging the car.
One area in particular that influences the performance of the entire car is the section immediately behind the front wheels. The airflow that passes through the inside of the front wheels, around the chassis side and bottom and the ground is basically what the rest of the car has to work with.
So any unnecessary blockage or need to have large radiator inlets or large front brake ducts only reduces this airflow and inevitably limits overall performance.