Because she missed all of the 03-04 season except for Worlds, where she had a mediocre result. (And also missed 2003 Worlds, although it appears that they've wiped all the results from that year for everyone now that the 05-06 season has begun.)
Again, these rankings don't tell us who is the best, second best, etc., skater in the world at any given time.
They tell us who has had the best combination of results in international events across the last three seasons. In general, better skaters will get better results and more ranking points. But participating in fewer competitions, whether because you just don't want to, you're physically unable to during the week of competition, or your federation chooses not to send you, or any other reason, gets you fewer points, regardless of the actual quality of your skating.