Automatically change $config['base_url'] when site is uploaded

[eluser]renownedmedia[/eluser]
I made the following change to the config.php file so that when I upload a codeigniter file to any web server, it will automatically change the base_url() output. I can't really see a need to ever manually define this anyway...

Code:

$config['base_url'] = (isset($_SERVER['HTTPS']) ? 'https://' : 'http://') . $_SERVER['HTTP_HOST'] . str_replace("index.php", "", $_SERVER['PHP_SELF']);

Anyone have any reasons this is a bad idea? It also works very well with the base href code:

<base href="<?=base_url();?>" />