I think you've got the right idea.

The search engines won't keep crawling your site as often if there's nothing new to index, but your pages will continue to rank about the same until something better (not just "newer") appears. Or until they re-jig the algo! I have one home page that has been bolted to the top of its main SERP for 4 years - even though I've never changed my story on it and there are many new competitive sites.

Changes to improve customer experience make sense - but I figure that's the only reason to change!