Yes, if you play the Ul'dah storyline, you know this. Reanimating the dead IS ENTIRELY POSSIBLE in Eorzea. So don't tell me it wouldn't fit with the game, it's already in the game!

It's a secret dark magic now, but a continuation of this storyline could very well result in the knowledge of necromancy becoming more well known and BOOM: Necromancy class. I think that's a perfect idea for an expansion.