Incidentally i learned something useful: declare dependencies also for core modules because nothing is eternal!

There are a couple of other good reasons to declare dependencies on core modules. Many vendor perls (yes, I'm looking at you, RHEL) do not install all of core by default. If they decide to package your module and it depends on one of the as-yet-uninstalled but core packages, the dependency may be unmet. Help the packager by declaring the dependencies and it should all work more smoothly.

It will also help the p5p if you declare core dependencies so that they can more easily see which of the core modules are widely used when deciding what to remove from core in later versions. It is much easier if this is in the metadata.