Also, as the battery nears EOL, the runtime from fully charged decreases and the battery's internal impedance rises -- limiting the maximum current draw. In this case when the processor power draw peaks, battery voltage collapses and the processor crashes. Adding a large capacitor could help ride across these peaks, but Apple did not want to commit the physical space necessary.

Properly managed from a PR standpoint, this power saving software (optional) patch could have been a winner for Apple.