You're focused on the security of your own server, but an insecure or compromised front end can be used to leverage your site's utility or popularity to attack

You're focused on the security of your own server, but an insecure or compromised front end can be used to leverage your site's utility or popularity to attack your end users or be used against other sites. Just read up on XSS. Your server can remain perfectly secure and uncompromised while your front end drags your company or project's reputation through the mud.