"A robust package manager backed by a large open source software repository is useful for more than just convenience. It allows the user to test software they may have not previously heard of. Being able to quickly install a piece of software you've heard about to give it a test is extremely useful.
"We also need to have the ability to test things that may end up on production systems. Ruby or Perl modules, for example, are often needed when developing automation scripts. Of course, this often leads to frustration if we aren't careful. Say a fancy new Perl module is available via CPAN, so we install it and start to depend on it. Then when it come time to run the new script on production server, which probably don't use CPAN, we find out that the module isn't available as a package."
