If you are giving it away, I will too.
New York encourages me to fulfill a certain number of hours of pro bono work every year. It is not a requirement, but I like to do it because it gives me a chance to help people who otherwise couldn't afford an attorney. Also, I get to work on interesting projects that help society.
If you are creating something you plan on delivering to the world for free, I want to help you do so. This includes licensing your work in the Creative Commons, as copyleft, or open source software or hardware.
Patents and copyrights are useful for artists and inventors, but they are not always the best tools. Some ideas have a better chance of spreading if they are free to all.