After editing a page
pagename, ikiwiki redirects to
pagename/index.html?updated. Ignoring for the moment that ?updated seems like a bad idea to begin with, this should at least not introduce /index.html into the URL.
The "?updated" works around caching issues with certain broken browsers, web proxys, and/or webservers. These assume that since the "?" is there, the page is not static, or is a different page, thus forcing the page to be reloaded and the edited version seen. So no, not a bad idea, really.
Removing the index.html would probably break this workaround. http://foo/bar/?updated will redirect to http://foo/bar/index.html, and said broken software will then display its old out of date cached version.
So, not changing this.