It would help prevent the sort of accident that occurred to the Air Florida B737 at Washington National in January 1982, where insufficient thuust was set and the aircraft was not accelerating adequately. Such a condition would have been "flagged up" by the monitor early in the t/o roll. It is very sensitive to subtle under-performance which could arise if say there was a binding brake unit or the aircraft was overloaded. There was a relatively recent case of, I believe a B747, which took off 10 tonnes over weight and consumed most of TORA just to get airborne - this also would be a classic situation in which the Take-off Performance Monitor (TOPM) could alert the crew that all was not as it should be, allowing an RTO from well before V1.
If you are interested in seeing the system in action and would like to take part in the trial please do get in touch and I can send you further information.