This sounds useful for when you forget something that happened chapters earlier or when you space out and need to figure out what's happening. This feature should work for the user, author's shouldn't be able to deprive me of this tool.
I could see this being useful for that.
I can also imagine a character interaction graph, animated by chapter.
Oh, and pronunciation. The Sun Eater series is eloquent, but the names are inscrutable without having heard a few of the audio books.
Ok it's not just me that gets to the end of a page and it's like the page didn't exist.
On the other hand the times I use the search function on the ereader most are when I stumble across a continuity error. It would be interesting if a story-reading AI can be used to detect those. Not that I want there to be less human editing in books, if anything we seem to need more.
As another example, I read the Aubrey-Maturin series earlier this year. Many times I would have liked a quick summary of a previous voyage or of a political plotline or something.
Don't be so judgemental.