I think this is a good idea since it focuses on an overall benefit for the site as well as for the artists and users.
Also keep in mind that not all of the top 20 authors have Journeyman level and that level is not required to benefit from the revenues. All that’s required is a paid subscription and fair quality uploads.
As far as detractors complaining for paying for something, the only thing they are paying for is a subscription to support the site and to have limitless downloads. Stardock will be the one taking a percentage of 'THEIR' revenues and awarding it to the authors in a fairly distributed way, so authors shouldn’t feel as if they have to comply or offer any kind of support or updates of their work.
On the issue of authors selling their work, it will not be done thru this idea. As far as I know (and if I understood correctly) the selling of premium skins will be a part of WC2K5 and it’s a feature offered only to certain authors (Masters and such)
Top authors as they stand right now, are people that have continuously contributed to the site and (obviously) are putting out work that people find very appealing otherwise they wouldn’t be on that list. In the past 2 yrs I've seen many artists come and go, a lot of them give up because they don’t get downloads, or get negative comments or simply get bored of skinning. That is why this idea is good, because it will encourage and give an incentive to the artists to strive for better quality work.
Regardless of the pros and cons, I think the idea is good enough to give it a try. Heck....it's so crazy it might just work