Besides which, running Perl::Critic on old code is going to dishearten folk, not make them happier

Take a look at Test::Perl::Critic::Progressive. It addresses the issue with having to maintain legacy code without it having to fail critic policies. Of course if someone goes in and starts changing that code the test will look at it and fail it if the new code does not support current coding standards.

It is a good bridge between legacy and new code.