What was the point of ScarJo?

I couldn't figure out why she was in this movie at all. Her character served no purpose. I mean, OK, I guess it shows that he's nailing the hot sommelier at work and that he thought his life was pretty good before the review. But that was it- she was a prop and I don't think the movie would have lost anything by cutting her out. Meanwhile, the Martin character was thinly developed in the first act and suddenly he shows up on the scene as Carl's starting his truck business and is suddenly the most loyal friend ever. Wouldn't this movie have benefitted from cutting all of Johansson's scenes and spending that time developing Martin's character instead? Maybe showing that they were really friends, and not just friendly co-workers, so that it doesn't seem so out-of-the-blue when this guy from earlier in the movie who you barely remember shows up across the country to help him out?

Also, the scene in Austin dragged on for an ungodly amount of time. Otherwise, a solid movie.