I give them money every month because their archives are essential to preserving our history. Not to mention, they have really saved my bacon before when I really needed to read some technical blog published a decade ago that has since been lost due to the website being reorganized or even being completely taken down.

Even though it takes a lot of bandwidth, I think preserving the source code on GitHub is an invaluable service and hope they continue to do so. I didn't know they were saving the zip file of every release, but I can understand why. It gives you point in time snapshots more easily and who knows how easy it will be to use a git repo from today 100 years from now. ZIP is a much simpler format if it needs to be reimplemented and is used all over the place.