Taanis Esther is the day when Esthers fast (or else it would be Taanis Mordechai). Why do we read Vayechal on this day?
All days are celebrated in the same way they were first celebrated.
- Pesach - we eat Maztas the same way we did the first time.
- Shavuos - we eat Cheesecake just like we did the first time
- Tisha BeAv/17 Tammuz/10 Teves - we fast just like Jews did inside the walls of Jerusalem.
When you can't eat, you might as well declare a fast and read from the Torah. However, when only Esthers fast, they can't read from the Torah (since they're women).
Since we're trying to recreate the original fast when only women fasted and no one read from the Torah, why do we read from the Torah and specifically Veyechal?