Basically there is a skill set gap. Nearly every one likes to contribute to a project this big and significant. But it will need much application of effort, time and energy to even get started and do something significant. Given most people have to tend to their full time jobs, have responsibilities (both financial and in other kinds) and are badly strapped for time. It will definitely require more than just 'trying' to contribute significantly to Perl 6 kind of a project.
Also not all people are altruistic like the current Perl 6 contributors(I have utmost respect for the current contributors, All of them Jonathan, Masak, Moritz, Larry, Patrick.. I mean every one who has contributed). People tend to think learning as investment in time and effort rewards of which they can reap later.
So if you are expecting people to invest in something like Perl 6, you also need to bring it out ASAP. I don't want to get into another 'readiness' debate. But the fact of the matter is, if some one asks you if they can simply go and use Perl 6 for all things they use Perl 5 today- Your answer will be a straight 'No'.
I am willing to bet that once something you yourself call 'production ready 6.0 release' is out. Module contributions will come in floods. But until then most people are going to stick with they think is going to be around for a long time. And that's hardly surprising.