This is a great suggestion!
You should add near an existing install how much space is taking.
For ecample I decide to install Wordpress or Live helper chat in the Webuzo panel so I search live helper chat and I install by using the Webuzo Softacuolous script installer.
Now I can use Wordpress or live helper chat and after many month I want know how many storage space is taking this install so in the page where I see wordpress or live helper chat installed near the version you may show space is taking this install.