I asked E-on if I could use one of there meshes once in a contest that ended up being commercial. They said sure. Key is to ask. People ask me all the time. My stuff has already made it on one of the cards. That's cool. What people are trying to prevent is that companies minning the vast public domain for material they can use for free. That puts the stop to that. What's even more funny is when a company discovers that they are using your material in there product and have to find you to get your permission.