cpanel users should be allowed to activate and deactivate this feature. If I have a subdomain and password protect it, the custom 401 error will never work even if I put something in the .htaccess file to change the error pages. You will always see a message that says 'Additionally, a 401 Authorization Required error was encountered while trying to use an ErrorDocument to handle the request.'

If the feature could be activated and deactivated for specific domains then at least you would would not get the addition error. Or even better find a way of getting the custom 401 error page to work with password protected subdomains. Many be there is some kind of fix that could be put in .htaccess, but I can't find anything.