Copy-left licenses, like the GPL, are designed with user freedoms in mind whereas other licenses are not. For a long time I failed to understand that fundamental property of Free Software. I always saw licenses like the GPL as restricting my freedoms as a programmer and entreprenuer. I thought how is this "free software" free when it restricts my freedom?
I thought being free meant I and anyone else could do whatever they wanted with the software, including using it in proprietary software. Doesn't that seem more free than restricting what I can do? As a creator of software I also felt like Free Software was restricting my rights because it infected my software, forcing me to do something and that sure didn't sound like freedom. This annoyed me to no end. I often wanted to use copy-left code but it happened to be incompatible with the license of a project that I was working on and so there I am with the code already written to complete a task and I couldn't use it. It sure didn't feel like freedom. What I failed to realize was that I was putting my freedoms as a creator over the freedoms of the users, and to some degree, the freedoms of my future self over my current self.
In a lot of ways it is similar to putting a corporation's rights above the rights of the workers. It often gives the power to the entities that already have power and takes power away from the larger group of users and subjects them even more to the corporate class. Is this what we want?
As creators I think we must make that evaluation with our software when choosing a license. What is more important to us: the freedom of our users or the freedoms of the creators and entities that control the software?