|laziness, impatience, and hubris|
Do you have any idea how often people set out to create new languages?
Most never complete them. (Though Roger Browne is putting enough energy in that I wouldn't bet against his completing this one.)
The vast majority of those do not become widely used That's a much harder barrier.
Let's examine his value proposition for a second. He is aiming for people who want to use a high-level scripting language centered around design by contract and would like to interoperate with the Parrot versions of Ruby, Perl and Python. That means that his success depends on there being workable Parrot versions of Ruby, Perl and Python. I've already talked about why I don't see Parrot developing a version of Python any time soon. From what I've heard, the Ruby community is singularly uninterested in Parrot. And I have good reason to believe that Ponie isn't going to be delivered in any reasonable time frame. Without Ponie, there is no impetus for anyone other than enthusiasts to be particularly interested in Perl 6 on Parrot. (Particularly not now that pugs is starting to target Perl 5 bytecode.)
So unless I'm wrong about one or more of the above, his project can't become popular unless someone comes up with an unexpected killer application for Parrot.