For a simple site like HN you won't see much benefit in rewriting it. Complex, heavily-styled websites are where HTML4/5 shine.
The biggest benefit is simply separation of duties (context - html, format - css, function - js). It looks nasty as hell and is a pain to deal with when html, tag formatting attributes, css, and javascript functions are all combined in single tags, systemically throughout the entire site. Separating them all both reduces code reuse and makes the whole thing much more readable.
Also, implementing something like CSS Media Queries would be 'interesting' without separation of concerns.
Comments
For a simple site like HN you won't see much benefit in rewriting it. Complex, heavily-styled websites are where HTML4/5 shine.
The biggest benefit is simply separation of duties (context - html, format - css, function - js). It looks nasty as hell and is a pain to deal with when html, tag formatting attributes, css, and javascript functions are all combined in single tags, systemically throughout the entire site. Separating them all both reduces code reuse and makes the whole thing much more readable.
Also, implementing something like CSS Media Queries would be 'interesting' without separation of concerns.