Features - unnecessery dependencies.
 

Is it only my opinion, that installing PostgreSQL, MySQL and Dovecot when someone wants to install phppgadmin, phpMyAdmin and squirrelmail is generally a bad idea? Database servers as well as mail servers may be on a separate machines. The web clients may be configured to work with these external servers. It's a common setup to diverse services on physically different servers.

Regards,
Filip.

if you ask about installation of ISPmanager, that you may change "custom installation" or d deinstall "phppgadmin" and other after installation.