I'd like to see this as well. I look at it as "SERP Freshness". What I mean by this is how old the posts or pages are that show in the SERP. A way that this is useful is when we're looking to improve on something that's out there already. It's useful to know if the SERP is full of recent content or if some of it is out of date and old. If there is a lot of out of date or old content on a SERP then there is a clear opportunity to create an up to date piece on that topic.