To me, Ashe’s theme sounds ominous and sinister, like a villain’s theme.
Could it be that her hate and anger drove her to less than heroic ambitions?
I think most of the characters notice this about Ashe, Fran notes it by saying, almost as a warning:
You could destroy all of Ivalice if you wished it.
Ashe isn’t a villain, but her ambitions and struggles really bring out a dark side to her character.
She could have been as a freedom fighter with noble intentions. Of course, this would have made her character less dynamic. Thankfully, she wasn’t. But did the writers have to write Ashe as a bad person reclaiming their throne?
TBAAAGamer1 had this to say:
Ashe is the sort of person who, before meeting Vaan, wasn’t even against genocide, she was undoubtedly villain material.
it’s part of the reason why I even tolerated Vaan, Ashe’s entire character arc heavily relies on the fact that Vaan is quite literally in the exact same position she was in, yet doesn’t give a flying fuck about revenge in the way she does, he just wants to know why his brother had to die, not how to seek revenge. this is ultimately what causes her to change her mind about a variety of things and forces her to adopt a more heroic perspective.
And I believe she almost does go down the route of genocide. TBAAAGamer1 makes a good point about Vaan; he actually softens her, giving her humanity and the ability to forego her hatred. This is what the world needs nowadays.