Maybe the ISU felt thay had to put in age limits if they wanted to go with CoP judging. 15-year-old prodigies like Mao Asada can rack up the points by doing triple Axels, triple-triple-doubles, etc. The older ladies don't have a chance, no matter how many PCSs they can coax out of the judges.
At TEB Mao outumped the field by more than 10 points and won handily despite giving something back on the artistic marks. Maybe the ISU did not really intend for the NJS to work this way.
MM