You do lose the ability to make money off of software licenses when you include a stipulation that every recipient is free to redistribute your software's source as far and as much as possible at a price not exceeding the cost of the reproduction and distribution of the code, and that he is free to resell binaries of said software at any price. As we see with RHEL, if you try to do so, something like CentOS will come in and spoil the party.

There are times when this kind of sharing is good, but I believe if we were interested less in economic zealotry and more interested in individual freedom to control the software that runs on one's computer, we'd see a lot more people distributing source code. That would ultimately produce a net increase in freedom for computer users, even if the rules say you can only share modifications with people that have a rightful license.

Those that want to license under a copyleft are by all means free to do so, but we shouldn't exclude people that would be willing to distribute source code so that their users can control the program themselves, but who are not willing to switch to a support or subscription based business model. You can't make much significant money selling GPL'd software, you only make money by selling support contracts to BigCo. And that model is not applicable to everyone, even if it works out OK for database systems and Linux distributions.

Whether it's simple to copy or not, it's not simple to implement or design, and implementers and designers should be compensated even if their work can be reproduced at minimal cost after its initial production and release. A car's physical properties that make it much more difficult to copy have nothing to do with whether the hoods should be opened or shut, and whether rightful owners should be free to tinker around inside.