In my opinion, it's not that the content on CB is less important than other areas, just that the sheer volume of answers on this section does mean it tends to dominate the 'recent posts' box and questions in other topics may be missed as a result.
I don't think the same applies to jokes because the joke section isn't as widely used as CB.
Perhaps another solution would be to enlarge the 'recent posts' to show 8 or even 10 at a time - but I don't think the Ed would do that, unfortunately, as it would cut into his advertising space.