The reason for not changing intensity was relayed to the airlines when installed. The high intensity lights are linked to the transmissometers which provide the RVR. If the intensity is lowered, the RVR readout in the tower. I.e. Brighter lights, better penetration, duller lights, less penetration. With lower intensity, the RVR readout may be less than your minimum. ATC is not permitted to lower the intensity when you break visual as this could affect the following aircraft. When changing from low to high, the readout does not immediately update as the system needs about 15 seconds to compute the readings from the three transmissometers for that runway.
Unfortunately the AIP doesn't seem to have kept up with technology. Reference AD 1.1-31 para. 5.12.5.