About the distribution between authors: You already explained the reason that most people using flattr are authors themselves – because so many people are authors nowadays.
And the people who are authors also are the consumers of other authors and the ones who know the value of this work. So speaking big: Maybe we have to stimulate more people to produce content and everything will work out just fine. 
But seriously and related to that. I rather believe it is not Flattr or any other specific service that we should promote, but blogs (etc.) and the culture that drives us. After all we’re having a similar “problem” here: Most readers of blogs are bloggers and rarely we are intrucing other more mainstream spheres – so how could Flattr achieve that?
This also would solve a problem I have with your “Register to a service and get our content for free”-approach of yours (that I believe to understand better now): I don’t actually want to be too much of an advertisment spokesperson for any enterprise.
It’s one thing to install a flattr-button and switch to kachingle, if it turns out to be the better service (or install some other additional buttons). It’s a pretty different thing to fully integrate a service in your site and pretty much rely on it’s succes. You’d lose a lot of independence.
Wouldn’t we actually have to promote a comparatively hard to change monopoly/oligopoly to make this work? Do we want that? I can see some of the advantages but I’m not too sure.
And a very important question: Can we make it easy to integrate those services? Because every fool can install a flattr-button. But I tried to integrate facebook on my blog once and while not being the most stupid person in terms of programming, I still failed pathetically.