From RMS himself: http://www.linuxtoday.com/infrastructure/1999062200505NWLF

From the linked article: "Because copying hardware is so hard, the question of whether we're allowed to do it is not vitally important. I see no social imperative for free hardware designs like the imperative for free software. Freedom to copy software is an important right because it is easy now--any computer user can do it. Freedom to copy hardware is not as important, because copying hardware is hard to do. Present-day chip and board fabrication technology resembles the printing press. Copying hardware is as difficult as copying books was in the age of the printing press, or more so. So the ethical issue of copying hardware is more like the ethical issue of copying books 50 years ago, than like the issue of copying software today."