It would have been nice if they'd added the long-form experience of playing as a typical Garlean while the Warrior of Light is completing quests for the Scions of the Seven Dawn as part of the story.

It could be the creation of a new character not dependent on the progression of the main character. Additionally, this character could be a "separate race" form of the typical Garlean Empire soldier.

Not only would it give a view of the whole story from the other side, but it would also open up possibilities to show some of the actions and decisions of the characters that we have not been able to see so far.
Additionally, it would give us the opportunity to create a slightly different endgame content for these characters, perhaps just for solo play, or it could simply be a character who disconnects from the Garlean imoeria at the end of their story and decides to fight for our cause.

It would need to play a classic msq to a certain point to unlock it.

Additionally, until we could join the right side we might be able to maybe fight other players in some special form of world pvp.