/wp-content can't be renamed

Up to WordPress 4.3.1 it was totally easy to rename at least the wp-content folder and with a bit more editing also the wp-admin. Why does this have changed?

Security related: “If you can’t hide which kind of CMS you use – especially a wide spread one – don’t use it because of security issues.”

I need some explanation now.
Do you want to build a bot network (due to a wide spread attack and with the JetPack plugin remote connection established on millions of blogs / websites)?

This worked till WordPress 4.4:

define ('WP_CONTENT_FOLDERNAME', 'assets');
define ('WP_CONTENT_DIR', ABSPATH . WP_CONTENT_FOLDERNAME) ;
define('WP_SITEURL', 'https://' . $_SERVER['HTTP_HOST'] . '/');
define('WP_CONTENT_URL', WP_SITEURL . WP_CONTENT_FOLDERNAME);

Please tell me and everyone else a solution.