I've had this debate with many people, skinmakers included. My personal opinion is anything i create I don't mind being used by anyone as long as its not to make money. If ripping parts of my skin helps a skinmaker to learn the trade then i have no issues with them releasing a skin that has my code included. It is always nice to get a little credit though of course.
However I know many people don't feel that way which is why i've refused to release things before, out of respect for their opinion.
Speaking of which, been working some more on Assymetry23
And no, before anyone asks this will never see the light of day, just a pet project to keep me in the mindset for when 24 comes out. I have plans for this years game