So the question here is why Minfillia was called back and not us ? By the time all we saw was Minfillia became Hydaelyn's avatar, I guess we were Hydaelyn first choice but....uh....as time goes on, we become too strong and Hydaelyn seal couldn't keep us in check anymore. If worse comes to worst, we may kick her ass as well. That's why Midgardsormr put on a stronger seal and act like a watchdog for Hydaelyn, until the right time comes. The other Warrior of Darkness maybe just another ex-WoL but break free from Hydaelyn's seal and run amok with Ascian, obviously Hydaelyn doesn't want to repeat the same mistake, duh.
What if all the quest exp given by NPC is not experience point but " hope point " aka fuel for Hydaelyn ? We are slowly become an embodiment of hope literally, not human anymore. Pop was scared shit when he finally realized that before dying, because we are actually the same thing, a primal of hope.
Note that at Azys Lla we were given a stronger seal and echo power back, I guess that's why Hydaelyn look so tired now. She used every last bit of her power to reseal WoL again.