It's really only trying to do one thing: get people excited about Perl 6. I envisioned the book attacking the problem from two directions, but that's a matter of methodology. I agree that it would probably be a lower percentage of people who learn Perl for the first time from such a book. That's what llama and camel are for, and they do a great job of it.
By your logic, it sounds like there's no reason to try and persuade anyone that Perl 6 is a good thing, they'll either like it or not. I don't agree with that at all. A good number of people don't like it purely because they don't understand it. The changes scare them, threaten their comfortable feeling of knowing Perl. They ask "Does it really make the easy things easy anymore?" The answer is "Yes." It still does, a little differently, but nothing to be scared of. These people (and there are a number of them) could be won over relatively easily.
I look forward to reading and giving my students the book that TheDamian writes.
P.S. I meant the O'Reilly "Perl 5 Pocket Reference".