For example I don't want the contact and cookie information page indexed by any search engines. I can disallow them by adding custom XML to set a robots meta tag¹, but why should they be present in the sitemap.xml if I don't want them indexed?
¹ Now I'm thinking about this any further, it would be nice too to have a dropdown on every page, product and category with the possibility to change the robots meta tag, like this: http://inchoo.net/magento/per-product-meta-robots-tag-control-in-magento/. Should I open another issue for this?