90 percent of rank and file users don't care if a site is the latest greatest version or not, they don't care if it's "kept up with the times" and they don't really care how it looks either. They care if:
1.) It loads fast and works well.
2.) It loads fast and works well.
Somethingawful dot com routinely has 5000-plus users logged on and posting at any given moment. Its users don't give a red rat's ass that it's a really old version of vBulletin. I can list at least a half dozen other such sites which aren't upgraded and are really really big busy boards.
I have always wished that this site could have a function similar to CSS Zen Garden, and offer some cutting-edge skins as options to members—to show what can be done with the templating system.