@gorice curious as to why you feel Galadriel's obsession with Sauron and conflict with the Elves is contrived? I felt the story did a good job of showing why the death of her brother specifically pushed her towards vengeance against Sauron, and how that obsession led to conflict with her society. It's not just about fighting a vague 'evil' or 'enemy', she is personally connected to the tragedy of it in a very real way. You are correct that her obsession moves the plot, as her refusal to leave is the inciting incident that allows Sauron's influence to grow. She's not doing the right thing, and the elves know it (much like Durin's father knows mining for Mithril is a bad idea, while Durin's drive to do so is driven by his personal friendship with Elrond). The show cleverly asks us to root for Galadriel and Durin to buck the council of their elders, while making their actions the cause of much strife to come. The plot then leads into the themes of the show, in trusting in Grace.
So we end up with Character driving Plot driving Theme, which is the backbone of good storytelling.