I get where you're coming from there, but unfortunately there are some legal implications with licensing. I'm don't know how familiar you are with the concept of free (as in speech) and open source software, but the most common way they license their code is under what's called the GPL, or GNU General Public License. It essentially says three things:
* You're giving the source code of your program away for free.
* Anyone can take that source code and modify it, use it, or distribute it in whatever way they wish.
* If anyone distributes a program based on your source code, they have to license the changes they made to your code under the same license.
The trouble is that given the requirements of the GPL, putting a restriction on how the art can be redistributed comes into conflict with the way the actual program is licensed, which can cause all kinds of hairy licensing issues that I can't even begin to wrap my tiny brain around.
So, self-defeating though it may seem, I have to have a limited selection of open licenses, because requiring the artists permission on a project by project basis essentially precludes that art from being usable in open source software. Mind you, I'm not suggesting that what you're getting at is a bad idea; in fact, I think it'd be really cool. It's just that for my particular purposes, it can't work, as much as I wish it could.
