Why use graphical illustrations on error pages?

These days you see it more and more. You click a dead link on a website and before you know it you're looking at a beautifully illustrated page with the code 404 written somewhere. Here are such examples:

Now don't get me wrong these are great illustrations, but they seem to have nothing to do with the content.

Are there some benefits to using illustrations for error screens? Does it minimize stress for the user?