Let's be clear about the point of patents first. Patents are for non-obvious inventions, and they exist to encourage sharing that invention's details with the public.
The idea is that a patented invention is novel enough that it's unlikely someone else would independently invent it, so the patent encourages the inventor to share all the details of the invention (and in exchange gives them a monopoly on it). Patents are specifically _not_ for good ideas that aren't non-obvious inventions. You can't patent the idea of "1 click buying" or "a time machine", only an actual invention/implementation that does those things.
I agree amazon's 1-click experience is a really good idea. It's also well designed and implemented. The question though is whether some other developer could, given the idea of "1 click buy", create this "invention".
I think it's unquestionable that, given the problem statement, many other developers of the time could have created the same thing.
In fact, a bunch of other developers have already created 1-click buy buttons, and I assure you the vast majority did not read amazon's patent to figure out how to write that code.
The fact that people can build this invention without looking at amazon's patent, to me, proves it should not be patentable. The general public gained nothing from the patent.