> If it ain’t broke...

Many of the comments below agree with this point. However I think the OP’s question is worth exploring. Good design that leverages fonts, colors, spacing, layout, etc. is supposed to make sites more usable and enjoyable. Why can’t we have a wiki that is easy to use/edit and looks nice and is accessible? These are not mutually exclusive are they? That being said, my recent wiki experience has all been using GitHub.