I understand that completely agree with you that Yuna was a highly anticipated figure star even before going into the 2007 world championship, but I don't think her reputation was higher than anyone else to give her a "high pcs" that everyone talks about.
If Yuna's reputation and PCS scores are controversial, then we can say that practically any skater who had won any world championships or GPF or even Junior series receive high PCS due to their reputation. Mao did 3A in her jr years, Miki did quad and was a super star in Japan, Koster was euro champ for I don't even know how many times, Mirai and Zhang were Jr world champs, Joannie was also canadian national champion for several times, etc etc. All I am saying that whenever we mention about reputation, high PCS and inflated scores, Yuna's name is mentioned as the "prime example." That's all.
In other words, I am very sure that if Mirai continues to improve and fix her UR, I am sure she will reach where Yuna is now. Mirai is 16, and she already won US nationals and Jr world, so she probably has just about the same reputation as the 16 year old Yuna did at 2007 world championship.