I think Mirai had a great programme to the music of Carmen, which really seemed to suit her personality. I feel that a skater can either try to be a certain character or interpret the music. In my opinion both selections are equally good.
I guess that's where our opinions differ - if someone is skating to music that's associated with a well-known character, I expect to see that character brought to life. Also, music like Carmen draws comparisons to skaters like Katarina Witt, which isn't a wise move for someone who's new to the scene and might not measure up. Mirai's inability to interpret Carmen (for me) hilighted her immaturity, when instead they could have chosen a program that presented her youthfulness and energy and other good qualities (like her sp). The Carmen program may have caused her to get lower PCS because it just looked very childish. Overall, I don't think it mattered too much this year - the judges weren't going to give her huge PCS anyways, since she's new to the scene. For next year, something like Rondo (mentioned upthread) would be a great choice - she could display her sharpness and quickness and playful personality. Violins seem to suit Mirai.