I saw this earlier on reddit and it's a great video.
I think this is one of the reasons I like Iorveth's character so much. He goes from being a simple anti-human elf "terrorist" to a character that fights for a place for elves to live alongside humans and dwarves. And his personality changes, and he seems far less bitter than when you meet him in Flotsam.
As far as not shying away fro character's negative traits and exploring them instead is one of aspects of character building, it's often taken to the extreme. It's important to remember that this is only one of many facets of the whole, and that a good storyteller must know how to balance characterization.
One of the problems is that people demand 'interesting' characters, meaning: individualistic, distinct, very clearly different than any other. It's not bad expectation per se, but it's often met with writers' inability to deliver convincing characterization which they compensate for by creating horribly one-sided characters.