For me the problem with GPL is simpler. I see a nice little library that someone spent two weeks on. It's GPLd. I would like to use that for the project I'm doing at work, which has 40 person-years of effort in it. So I can never use that 2 week effort code (because I'll be fired). The world is a little worse off because I now have to waste two weeks of my life reinventing the wheel, and so does everyone else who's not doing open source.
I see this argument a lot: programmers working at for-profit companies writing proprietary software feel restricted because they can't use someone else's work to their advantage. Of course, these same programmers don't have a problem with proprietary software licensing. I don't understand this viewpoint. Copyleft software is bad but proprietary software is okay?
I have no objection to proprietary software, because that is how people make a living. That proprietary software license is what allowed the author to quit his job and bring it into existence. The alternative to making software proprietary is not making it GPLed. The alternative is not making it at all!
A hobby is not a substitute for a job.
I would never characterize copyleft software as "bad:" the author has donated time and energy, and I am grateful. But it is less useful than it could have been. If you're going to write some software and give it away, man, just give it away!
