Actually, CPAN was not the first of its kind. CTAN, the Comprehensive TeX Archive Network beat CPAN by a couple years, and it's not an accident that they have a similar name. I find CTAN just as useful as CPAN, and for the same reasons.
It's extremely easy for any other language to copy this. All they have to do is follow Jarkko's advice to make something simple that other people can build on. Perl has the ecosystem because Jarkko and Andreas made a good foundation and then got out of people's way. Today's kids have too much technology, so they think a simple FTP archive is stupid. They try to build overly-complex systems which they then lose interest in.