Mine are to avoid enacting barriers to having my code used on systems where failures mean people could die. The GPL is not an ideal license for that, but there are worse licenses. One example of why the GPL is not an ideal license for that is that US federal law prohibits the GPLv3 in automobiles because it mandates tivoization. If choices are between good code under the GPLv3 and bad code under a license the law permits, the bad code is used and then we get things like Toyota vehicles' drive by wire being able to live up to the saying, "Always moving forward". In this example, this also affects people outside the US whenever the engineering is reused and I doubt any automaker would design 1 drive by wire for the US and another for everyone else using GPL code that is well known to be superior to their embedded garbage. This is far from the only example and not all examples involve federal law. However, if you write something good that could have a mission critical application, it is good enough that the alternative code is more likely to kill people and your principles are to exclude anyone who does not do exactly what you want them to do with it, you can have your principles, but people might die as a result. If deaths occur and those dying from it include the principled person who could have saved them, having those principles would be what killed that person. Having the developer die too in such situations is improbable, but it is something I consider when I ask myself "what do I want a software license to do?".