Do you remember how they swore upon the rock just two chapters ago at the end of Joshua? One generation should not make oaths for the children of the next. Did they not take into account that Joshua may well have brought all this up because of something he knew all to well? There were already foriegn gods in their possession for them to have to put away.
In the midst of such other foreign and exotic beauty it is hard to find one that unanimously stands apart. There must have been something more than beauty that set Esther so far apart so as to obtain such grace and favor. Thinking ahead through what will soon transpire I would say that it was a work of God.