I suppose repetition is necessary to aid learning. But surely anyone who wants to remind themselves of earlier events could just go back and read the earlier chapters. But you know it's those generations of monks who used to waste their time copying this stuff out I feel sorry for.
Having found Moses' book of laws, Ezra reads them out and gets everyone to start following them. Which they dutifully do. And then we need reminding of everything that's happened, again. How much more concise and to the point this book could be if the constant repetition was removed.