Yes you are correct, it grew to be one of the hottest Nintendo franchises when Awakening dropped. So maybe Fire Emblem isn’t underrated anymore per se, but rather it gets too much unjust hate by people who have never played the games. And they hate it with a passion.
Just look at the Smash community. Actively demanding to CANCEL existing Fire Emblem characters from the roster and sending death threats to the devs for adding “aNoThEr AnIMe sWOrdSmaN” as DLC from a new bestseller game. Disgusting.