This is interesting. Are you saying that if CC become aware of a potential emergency during the take-off roll (smoke in cabin, passenger trying to ignite shoe, etc), they cannot communicate this to the flight deck? If the plane has not yet reached V1, it can stop safely - is there not a procedure for alerting the flight deck to a reason to reject the take-off?
The airline I work for regard the cockpit to be sterile during the critical phases of flight. I for one am happy with this procedure, the last thing that I want is to contact the flight crew and distract them at an inappropriate moment. If I was to say to the pilots on the interphone "Oh my god, there is smoke in the cabin" and we were just passing V1, they might attempt to stop, go off the end of the runway and end up crashing into some obstruction that would cause a worse catastrophe than what would happen by continuing.
If there was smoke/fire in the cabin, ATC would give the pilots priority for returning to the airfield. All the appropriate emergency services would be lined up by the runway waiting for us when we return. The pilots would do a quick circuit and drop back in on the runway and then if necessary an evacuation would take place.
As I said before, sometimes it is safer to continue that to stop the aircraft.