Change is uncomfortable. Transitions aren't usually enjoyable - but they are absolutely necessary ... if we intend on growing. Passing the baton, moving from one stage to another, rising to another level, turning the page into a new chapter. These are all metaphors we use to describe transitions.
This is the "2nd Law" (actually just a repeat of the first.) The new generation needed it reviewed to them b/c they were about to face some new enemies and new struggles. The Lord knows we are forgetful - this book is full of reminders... don't forget God, His promises, your salvation, etc.