Unless a character is a member of your party, they are just plot devices, as opposed to complex characters. When you consider that the game needs to continue regardless of whether they are alive or not, their lack of characterization becomes clear.
I strongly disagree, assuming I understand what you're saying.
NPCs are part of the world. Your connection to the world on an emotional level is what makes it possible to experience an arc, or at the least, a warble. An important character like Thaniel living or dying should paint the mood in entirely different ways, all dependent upon your connection to that character.
The problem with emotion, of course, is that it has to be earned. You can't start a story with someone desperately crying in despair even if you, as the author, know why. The audience doesn't. The tears have yet to be earned.
So it is with the death or survival of a plot centric NPC. The result must be earned. And felt for it to be effective.
In short, there should be more characters like Rolan, not less.
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But all of that aside, just the whole concept of Thaniel seems unnecessary. I can see how it functions as a quest for Halsin, but wouldn't it have been more powerful to reveal that Halsin was the cause of Isobel's death, and to wrap his quest line in matters that addressed that issue directly?
