Dividing the topics up into pages makes it so that a post page won't become incredibly long and slow loading. Plus if it's a long topic, you can zip right to the part you want to read (the latest stuff).
If it's a discussion, you can refer to the pages (ex: "My reply to that question was on page #3").
I think it's a useful feature, better than what we had before. So we'll stick with it.