If you're asking if XML map is necessary in SEO, then my answer is YES! Creating an XML sitemap in your website and sending it to search engines is among the necessary task of an SEO campaign. In order to bring in more targeted traffic to your website, XML maps are necessary.
If you really want that your site should be read by Google than firstly Submit your sitemap in Google webmaster as well as create XML sitemap and add it on webmaster for better crawling and indexing by Google crawler.
It is not necessary but it is seriously recommended as the XML is easily understandable by Crawlers and also the webmaster tool advices for it. So I guess when two big daddy's demand it, it must be important!