The stories told about Walt is crucial to the story because that gives reason behind Chris leaving to go on his adventure, which is the point of Into the Wild. Chris' background shows readers why he left and what pushed him to want to be on his own. The part about Walt and how much it outraged Chris further shows how Chris just needed to get away. Without this piece readers would question Chris' intentions even more than they already do. Walt's story provides some insight into Chris' head.
Krakauer's story isn't necessarily crucial, but is very important. The addition of his personal experience further provides some explanation to Chris' thoughts. By having a similar background and a similar story, Krakauer's feelings can be paralleled with Chris', helping to fill in some of the blanks that people didn't know.
From the start I thought Chris was a courageous person just for the fact he pursued his dreams at all costs. These stories didn't change my opinion of him, but further justified him leaving. The feelings Krakauer had show what Chris could have been thinking which helps prove that Chris didn't just make a spontaneous stupid mistake. Walt's story futher pushed my positive opinion of Chris in that he was able to take what happened and the anger and use it to pursue his own life and be happy. Instead of wallowing in self pitty or taking out his anger on his family he chose to use it to find himself and become independent. Overall, both pieces helped justify Chris leaving and further prove Krakauer's view of Chris.