It's possible this already exists; if it does, I'd appreciate a comment indicating where. I understand this isn't the right place to be making feature requests; I'm just putting this here as a kind of public placeholder to remind me to submit it correctly soon.
Perl feature request: keep track of CPAN modules installed. When installing a newer version of Perl, identify all of those modules, sort them in dependency order, and install them. Ideally, one would need to configure it to do this, but the fact that it could do this would be indicated. Ideally, this would consider soft dependencies in its sort formula, so, for example, Test::Deep would be installed before Perl::Critic, even though Perl::Critic may work without Test::Deep. (However, in the case of a soft dependency loop, soft dependencies would be ignored for the afflicted modules.)
I want this, because nearly every time I've upgraded perl, I've found myself lacking modules I had grown accustomed to having in the old version. I admit, this does give me an opportunity to verify that my soft module dependencies are, in fact, still soft. However, I would probably be more comfortable with frequent perl core updates if these modules were included.
Note that I realize there are times when perl modules are migrated into the stock perl install (for example, Term::ReadLine was, originally, not part of the base install, but it is now), and there are other times when new CORE perl features obsolete a module. In these cases, it would be appropriate to eliminate the modules from the list. In the case of obsolescence, if the new CORE features include a different calling semantics (which will likely be the case), it would be appropriate to issue a warning pointing to the docs that detail the differences.