MoonWolf, thanks for your request. However, this feature could not be added because of security and performance reasons.
Let's say that AWB allows storing pages on main URL (like awbgenius.com/somepage.html). But what happens if you have keywords like 'sitemap', 'partners', or similar words which are reserved for some additional pages? If any visitor requests for page like awbgenius.com/sitemap.html, AWB will don't know what page (original sitemap or content page about keyword 'sitemap') to serve. It may also cause some security issues, so you are playing with fire if you perform these "hacks" now.
It could be possible after making some extra rules, but it will also require complete rewriting of AWB software, therefore it's impossible to use empty (blank) URLs now.