[aroberge]

Say you release code X under a BSD license. Someone incorporates a neat, but tricky to re-implement, feature and release the code under GPL. Everyone wants that new feature but, if they do, they either have to reimplement it without looking at the GPL source code, or they have to use the GPL license from now on (or, third choice, live without that feature). I used to release my code under a GPL license but found too many restrictions. The worst offenders were tutorials written where the code was GPL. Tutorials that aim to free you by giving you new knowledge should not tie your hands and force you to adopt a license if you want to use that knowledge.