I think the quests for her story suck. As you said, just a bunch of fetch quests and they take away the emotional impact and sense of urgency you're meant to feel. But I believe the story is meant to be analogous to dealing with a terminal illness. The hope and search for a cure that never comes, the fact that it happens to good people who deserve better, etc. At least it felt that way to me as someone who has experienced having a loved one diagnosed with a terminal illness. Story wise there were impactful moments but I agree that the quests were poorly and lazily executed. I'm glad they ultimately did provide a real chance at a cure in the epilogue but that was written after they finished her main story. (I also think this had to do with the fact that they were working on the canceled dlc at the time.)
I think this was already discussed in the Karlach forum, but the problem with that idea is the setting, the game takes place in a setting where her problem is pretty insignificant.
This is once again, a problem with how her story/quest is handled.
Should the quest explain in a satisfiying way why she can't be healed i wouldn't have a problem with it, yeah, it would be sad but at least it would give us a reason.
