It's painful to watch so many good developers giving away their best work for free, because they feel it's somehow their duty to do so. It's the same feeling I get watching fresh graduates working 100 hour weeks for these startups because there's free food and everybody else is doing it. You want to help, but the culture is just so well geared towards attracting new kids to exploit and convincing them that the exploitation is a good thing.
It's like a cult. Except that nearly every software developer in the world is in on it.
I'm certainly not helping the situation personally, and will happily use whatever Open Source software product helps my business for free. But I do hope that people come to their senses at some point and stop peer-pressuring each other into continuing to spend so much effort polishing good software only to give it away for free.
The things you build have value. They're making other people billions of dollars. Charge accordingly.