The entire last episode resulted in Joel committing to protecting Ellie and bringing her west. Prior to reading Bills letter, he didn’t really give a shyt about her. Now he does…which is literally the entire point of the story.
So, you know…some plot progression, I’d say.
Pick up on threats better on the ground than laying in a trucki woulda slept in the car, why the hell would i sleep on the cold ass ground