It's not about disk space.

I have to upgrade my systems OS on a regular basis, and because I can't have downtime for more than a few minutes, I build a new system with the new OS version and swap it with the old one. I need the new system to act just like the old one, so obviously I want to install all the perl modules I had on the old one. Except, it can be a pain trying to install a massive autobundle when certain flakey modules don't install correctly or they fail to have the correct dependencies listed etc... So, it's nice to leave out any modules I don't actually need.

Also, it's nice to keep things tidy, and it's just fun to know what gets used.

--Pileofrogs