VE works well-enough for pages that aren't signed, except for ones where the pages rely on fiddly or partial wikitext munging, like the Template and MediaWiki namespaces. Consequently, we should be OK to enable VE in a larger number of namespaces, rather than just NS_MAIN and NS_USER:
- wgContentNamespaces generally?
Part of the fun are things like the portal namespace which is defined per-wiki.
See also bug 55792 for comments about enabling VE in all namespaces, and why I think that's a bad idea.