index.html with simulating 403 error

[eluser]Unknown[/eluser]
Hello, why in sources of CI all system and application folders "closed" with index.html with 403 error.

Why not to use htaccess "deny from all", with this it can be removed from all files

if (!defined('BASEPATH'))
exit('No direct script access allowed');

[eluser]WanWizard[/eluser]
It is an extra security measure, in case the user doesn't have that in the .htaccess (or doesn't have a .htaccess at all), and has an apache config that allows indexes to be shown.