I suspect it's "improvements" in storage that are to blame. All Granny Smiths are clones from the same tree, and they were grown successfully in many different

I suspect it's "improvements" in storage that are to blame. All Granny Smiths are clones from the same tree, and they were grown successfully in many different places, so I don't think climate is the problem. Probably it's some new storage technique that lets them keep longer without rotting, at the expense of taste/texture. I see problems with bananas too that I think have the same cause, where they turn directly from green to brown, and I don't remember that happening ten years ago.