How to create a useful 500 internal server error page

I'm trying to create a useful HTTP Error 500 Internal server error page and the recommendations I have found and the live examples I have stumpled upon use a very simple layout. They basically include:

  • a logo
  • a headline
  • a message
  • and a couple of solutions how to fix it such as reload the page, come back later or contact the webmaster.

What are the reasons not to also include the main site navigation or a search bar so that the visitor could find another page on the website? Is it technical or is it just to keep an focus on the error message?