The press release naturally doesn't mention it, but I'd guess this was done at least in part because the release of the back issues for free public access became a fait accompli with: http://news.ycombinator.com/item?id=2789709
People have been pressuring them for years to make these open-access, arguing that a non-profit society dedicated to spreading public knowledge ought to at least make the very old historical articles freely available to the general public.
People have been pressuring them for years to make these open-access, arguing that a non-profit society dedicated to spreading public knowledge ought to at least make the very old historical articles freely available to the general public.