I am not a developer, but a sysadmin, and I don't know much about perl since I haven't used it much in the last 15 years. But I do know that if you have to run commands for CPAN to install some packages your developer says are required, your in for a bad day.
I agree, but part of the problem is that CPAN is old, i.e. it's been around for years, so you can find very out-of-date documentation and advice on the web about how to install packages.
For example, if you find a page suggesting you run 'perl -MCPAN -e shell', and you try using that, you'll probably have a very bad time. Watch out for it trying to upgrade perl itself! There are newer, saner and nicer ways to access CPAN and install packages.
There's also possible conflicts between CPAN and your distribution's own packaged perl modules, but that's a common problem with any software you install yourself rather than through the distro's packaging scheme.
Look into cpanm, local::lib, the Cpanfile, perlbrew, and carton. There are multiple angles of attacking this issue that are better than the old CPAN shell.
Please investigate local::lib.
Perl6, on the other hand, is effectively another language altogether, and I hope they rename it completely to stop the confusion.