In the early days - back when Search Console was still called Webmaster Tools - the content keywords feature was the only way to see what Googlebot found when it crawled a website. It was useful to see that Google was able to crawl your pages at all, or if your site was hacked.
In the meantime, you can easily check any page on your website and see how Googlebot fetches it immediately, Search Analytics shows you which keywords we've shown your site in search for, and Google informs you of many kinds of hacks automatically. Additionally, users were often confused about the keywords listed in content keywords. And so, the time has come to retire the Content Keywords feature in Search Console.
The words on your pages, the keywords if you will, are still important for Google's (and your users') understanding of your pages. While our systems have gotten better, they can't read your mind: be clear about what your site is about, and what you'd like to be found for. Tell visitors what makes your site, your products and services, special!
What was your most surprising, or favorite, keyword shown? Let us know in the comments!