At what point in time (and, more importantly, why) did the .htaccess addition for the Ceon URI Mappings become so complex?

I recently upgraded a site from zc155f and this is the only addition to that file ... and it works just fine:
Code:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* index.php [QSA,L]
</IfModule>