I believe that's incorrect <span>parallelism</span>.
Also, there should be a "you" between who and are.
I would think it is to communicate Jen’s anxiety because she seems scared and she’s talking in short sentences like she is trying to gather her thoughts because she’s nervous.
It shows she is open minded because she still considers it even though It is a old tradition and her family is more modern.
It suggests that Groucho believes the writer of the original letter knows as little about the city of Casa- blanca (his history is filled with absurd details) as he knows about how different the Marx Brothers' film A Night in Casablanca would be from the famous Casablanca.
