JAR-OPS makes reference to a deterioration in RVR not in aircraft equipment or capability. To continue the approach with reduced operational capability could lead you wide open to criticism in the event of an incident.
My user name derives from one of my first aviation cases where a commercial pilot continued an approach below minimum RVR and landed short of the runway by about 150 meters. He was prosecuted for reckless endangerment by the CAA and was convicted of negligent endangerment.