Eww, pay-for django extensions.
People need to eat, and writing open source software to provide for themselves seems like a much better model than doing it for free in their spare time off from some proprietary coding job.
People who live and work outside of academia (and, lately, inside of it as well) for long enough eventually figure out that this perspective is naive. It just takes a while to lift your perspective far enough to see a larger part of the picture.
Personally, I'd love to see more of a marketplace for OSS projects. Open, collaborative projects that still make enough money to fund continued developement seems like a pretty good thing all round to me.
That said, a better question would be what's the problem with "paid for Django extensions"? If you don't like it, don't buy it.