The neutral zone surrounding the reaction centre of the photosystems in the thylakoid membrane are important to prevent the escape of electrons. This is due to the ability of electrons to jump to other, more positive molecules, in an attempt to neutralise the complex. This is not desired in a photosystem, as charge and excitation both need to be tightly controlled.
By preventing electrons from transferring between the reaction centre and the light harvesting complex, excitation energy must be transferred by Förster resonance energy transfer. This ensures the flow of energy is towards the catalytically active reaction centre, where the special-pair chlorophyll are located.
Photosystem I transports electrons across the thylakoid membrane, through the reaction centre. If it were not possible to maintain the electrons within just the reaction centre, the transport process would diminish and not be feasible.