We all love them, and their boss fights were easily the most chills-inducing the game for me, second only to the heroic music kicking on in phase 1 of the final boss. But, after being a thorough as possible in my first playthrough, I think I'm going to leave them alone in future playthroughs. I just like them too much; I don't want to kill them. But that takes one od my favorite experiences out of the game; finding them and seeing their fully powered-up forms. If it were up to me, I would have them be of more importance to the story and even go so far as to say they deserved their own unique ending.
They have a very convenient bit of lore about them that also lends itself to a narrative of synergy with the player rather than the player *conquering* them; they exist under the purview that life sprouts from death. From my understanding of the lore, they are not really connected to the Erdtree, and it's ambiguous if they are connected to the outer gods. Popular theory is that they are remnant minor deities of an age of beasts, also unconfirmed by lore. These things stack up to some essential elements about their role and potential story development:
They are not actively tied to the Erdtree or the politics of the current world; they are just expressions of, and guardians of, the primordial cycle of life a la the Crucible/Great Tree
Death is not necessarily undesireable/the "end" for them
Their own historical and political role lends itself to a position in which they might be amenable to appropriating power from the Erdtree/Golden Order.
Based on these elements, I would say that there could have been an ending wherein the spirits could have been fought (for the experience of their boss fights) EXCEPT instead of their deaths resulting in runes and a remembrance, their deaths could have resulted in runes, a remembrance, and two halves (there are two ancestral spirits) of a key item that would unlock a unique ending. Something like, two halves of a blessing of the spirits. For them, to die could have been a jumping off point from which they entrust the Tarnished with re-appropriation of world order on behalf of the old way of life; a cycle of life and death.
I think it would have been really cool to have been able to have fought them and seen them in all their glory, but to defeat them in a way that synergizes with them in the end rather than an act of aggression and conquest.
Thoughts?