I agree with stone_and_star here, and she is much more knowledgeable than I. Still I can't resist sticking my nose in. :) Esther is dealing with a complex political situation. Being able to solve the problem and handle her husband within the constraints of the day is a strong testament to her intelligence. Although Mordecai told her to take action, it is clear in the story that it is a closed palace, so Mordecai would not have been in daily (possibly even weekly) contact with Esther once she was married. Esther therefore made the final decision to take action and took the action on her own. You have left out the fact that Esther fasts with her maids for three days before approaching Ahasueros. Her faith is tested, but she risks her life in a much more immediate way than the Jews as a whole are at risk at that point, and she does what needs to be done.
I also wanted to add that there are positive feminist implications in the practice of Purim (as opposed to its text) that should not be overlooked. The book is named after her, she's extolled as a strong positive role model, she's portrayed (at least in all the synagogues I've belonged to, which admittedly aren't a fair spectrum) as the heroine of the day, with Mordecai getting more of an assist. It's very rare to have an accessible positive female role model in this tradition. (I learned about Ruth and Deborah in school, but their stories are harder to sell.) Most of the other female characters, such as the matriarchs, are even more passive and less believable as feminist icons. To have her name on the best (from a kid's perspective) holiday of the year is worth something. Plus, Esther's fast is the only fast day on the calendar named after a woman.
Edit: Oh yeah, I forgot to say, you are completely right about the Vashti situation. It's really an embarrassment that some versions of the story try to sell her as a sort of villain. There's no forgiving how she is treated, and in a good hollywood movie version Ahasueros would have to be punished for it at the end. It is sort of stunning that he gets of scot free, actually.
I also wanted to add that there are positive feminist implications in the practice of Purim (as opposed to its text) that should not be overlooked. The book is named after her, she's extolled as a strong positive role model, she's portrayed (at least in all the synagogues I've belonged to, which admittedly aren't a fair spectrum) as the heroine of the day, with Mordecai getting more of an assist. It's very rare to have an accessible positive female role model in this tradition. (I learned about Ruth and Deborah in school, but their stories are harder to sell.) Most of the other female characters, such as the matriarchs, are even more passive and less believable as feminist icons. To have her name on the best (from a kid's perspective) holiday of the year is worth something. Plus, Esther's fast is the only fast day on the calendar named after a woman.
Edit: Oh yeah, I forgot to say, you are completely right about the Vashti situation. It's really an embarrassment that some versions of the story try to sell her as a sort of villain. There's no forgiving how she is treated, and in a good hollywood movie version Ahasueros would have to be punished for it at the end. It is sort of stunning that he gets of scot free, actually.