Another question I think is not getting enough attention here is, under what terms such data (and code) are available. In particular, what happens if the rights to the data are not held by the paper authors? Say, I write a paper using slightly modified brain images from the IBSR repository (just as a random example of a shared data resource). I cannot distribute those images to anyone because the IBSR use conditions prevent me from doing it. I can give the modified images back to IBSR and ask them to make them available on my behalf, but they are not obligated to. If they do choose to distribute the modified data, they could impose conditions on them that some may consider unreasonable. Are these data then still formally available? The same goes for any other data repository that imposes non-proliferation conditions upon data users (which is pretty much every such resource that I am aware of).