It's still pretty new, so the library infrastructure sucks (but getting better every day).

I'm only peripherally involved in the community, but at this point, it seems people are using it primarily for small utilities and such.

Lots of "sane" people would (at least for Perl 5). I know it's not "the new hotness", but Perl 5 is still an incredibly useful language that a lot of people know (present company included). There are extensive libraries available for doing a lot of things that need to be done in day-to-day business. There are plenty of perfectly legitimate places to use it in new development.

The Perl 5 porters development list has a decent amount of traffic ( http://www.nntp.perl.org/group/perl.perl5.porters/2017.html ). And Perl 5 still has a good number of active contributors ( https://www.openhub.net/p/perl/contributors ). Also, The CPAN has plenty of modules with daily activity ( http://search.cpan.org/recent ).

Even if you would not choose to do new development in Perl 5 (because of other language preferences, or whatever), that does not mean it is unreasonable (or "insane") for others to do so.

Whether Perl 6 will ever catch on, I don't know. The language has a lot of features that look interesting, and I think it could also be very useful. I personally have not had time to look at it much yet, but probably will when I don't have higher priority things in life preventing me from doing so.

Me, albeit a small project, it was really fun to work on; it was an interactive blog.