lastmod in sitemaps for blogs

This question has been doing the rounds in my head for a while since completing #PaPy. Why does a blog’s sitemap.xml need to have <lastmod>? According to the specs, the tag is not mandatory and besides that, it does not really fit into a blog, I don’t think. At least, I cannot justify using it as I fail to see its purpose for this type of website.

<lastmod> is used to provide the date of last modification of the page. Since this is a blog, why would I go back and modify my posts? OK, I might read one after publication and realise that there is a spelling mistake, correct it and republish it. Do I really need to notify search engines of this change by tracking the last modification date?

I don’t think so. Perhaps if my pages were dynamic, then I would definitely have a need for this. But seeing as this is a static blog — key word being “static” — I’ve made up my mind.

Today, I pushed through a change to remove the generation of <lastmod> in the sitemap output by PaPi.