I'm almost certain someone RFCd that for Perl6, although a quick scan of the RFC list yields nothing. I know for a fact it was discussed in the language mailing lists. Actually, there was a whole sub-list working group for the strict pragma!
Perl6 RFC #16, by Daniel Chetlin makes the argument that the strict pragma should be left more or less the way it is. Here is a brief synopsis of his reasoning, which was echoed in the mailing lists when the scenario of turning strict on by default was suggested:
=head1 ABSTRACT Perl5 is usable with no hassle as a quick-and-dirty problem-solver by default. It is ideal for one-liners, short scripts, and quick hacks that have no need for extra protection or error-checking. It is also great for large projects by making use of the C<warnings> and C<strict> pragmas. Perl6 should not make the one-liners, short scripts and hacks need to jump through extra hoops to get the "lax" behaviour which is default in Perl5; the point of using Perl as a quick-and-dirty tool is that you don't have to do anything extra.
You can view the RFCs and mailing list archives at http://dev.perl.org/.