The teacher's use of role-play, letter writing etc. is neither better nor worse than the material in the textbook: it is simply different because the teacher thought it would be more appropriate for a particular group of students and their teacher on a particular day.
The example shows how a teacher takes an original textbook idea, adapts it, putting in his own activities whilst staying faithful to the language and topic of the writers. He is perfectly happy to use the material if necessary but simply wants to give the lesson his own 'spin'.