But https doesn't 'let you know for sure that the content is exactly what the owner of the site intended' as it doesn't protect you from xss
Than you fix the XSS vulnerabilities and implement CSP. Shitty security practices is not an excuse for more shitty security practices. https://developer.mozilla.org/en-US/docs/Web/Security/CSP
When you visit "blogs, news websites, etc" do you think there's no value in being able to know for sure that the content is exactly what the owner of the site intended? Even though ISPs have proven themselves willing to intercept and modify that content in transit?
http://arstechnica.com/tech-policy/2013/04/07/how-a-banner-a...
http://arstechnica.com/tech-policy/2014/09/08/why-comcasts-j...