Esther knew she had to tread lightly. Ask for too much, and she'd find herself queen no longer.
We approach this with a different attitude today because we're used to governments that, thank G-d, give Jews a great deal of freedom.
To illustrate: Rabbi Moshe Feinstein's younger years were spent living under Communist Russia. There was no way you could attack it head-on, if you did that you were shot. You tried to accept it as best you could and cautiously work with/around it as much as possible. ("Of course we're not condemning the great Soviet co-ed bathhouse; we're just old-fashioned and too squeamish to use it, and if the Jews never bathed it would create a diseased population likely to contaminate everyone else; thus could the Jewish men and women please each have a few hours a week for private bathhouse use?") Thus it's no surprise that in the late twentieth century, when many Americans were demonstrating for Soviet Jewry and yelling "let my people go!", that wasn't Rabbi Feinstein's world. He thought "please let my people live" (i.e. improved conditions within the USSR) was the most you could ask of Russia.
So I don't think Esther's statement sounded outlandish to many Jews, even fifty years ago.