What is the point of the Resurrection Spell?

This thought been nagging me for a few days and I have to ask, why is the Resurrection spell even in the game (bring someone back to life up to 100 years after death)?  It makes no sense for gameplay.  I will never need to use it on my own party members when I also have Raise Dead (bring someone back to life up to 10 days after death), and Revivify (bring someone back to life up to 1 minute after death).  I keep them prepared just in case, but I never had to use either of those during the Crown of the Magister and Lost Valley campaigns (I have the deadly and merciless AI options enabled).

Even though my cleric has these spells (and a few scrolls too), when one of the essential characters I was forced to bring along got knocked out in combat, I didn't rush to their aid because I though I could just use Revivify or Raise Dead on them after the fight, but instead I get a game over screen when they died and had to redo the fight.

Gameplay reasons aside, it also creates a bit of a plot hole.  During the quest Thieves Among Us, there's a scene where they're talking about using an ancient spell to talk to the dead on Thadeos to find out who killed him.  You have to wait through the night so Maja can prepare it.  I just couldn't help but wonder why if a spell such as Resurrect exists, why didn't they resurect him when he was found dead.  You could have at least put some sort of explanation in there, but it still doesn't change that it's still useless in the game, unless there's some place later in the game where I can resurrect someone that's been dead for more than 10 days.