Copyright-free software should be available for download if the author of that software is willing to share their software without a fee. It should be determined by the author and no one else. If they want to copyright their material, that is their choice. If they choose to put it out there for free, and they are happy with it, no one else should have any influence regarding that.
Oh, I just cannot wait to read the arguments against this. Copyright free software has existed in one form or another as long as there have been computers. I've made some of it myself, as a matter of fact. The Open Source movement is an example of how yes, it should be allowed.
If there is no copyright on the software, there's no reason not to share it freely. Since downloading is the way most software is propagated nowadays, that's how copy-right free software should be distributed. It would be silly if it was only available in disk format. Copyrighted software on the other hand, should only be downloaded from a rightful provider.
If the author of the software chooses to make it copyright-free, then there should be no restrictions on the ability to download it. It is up to the author of the software to choose whether or not to capitalize on his or her copyright, not the decision of some legal body.
Some software available for download is free, but it is not copyright-free as the original creator remains the owner of the software and its concepts. Providing copyright-free software doesn't indicate that the price would be free, so asking this question seems somewhat useless. Free and copyright-free are two totally different things.