Actually I think Web 1.0 was reminiscent of the mainframe terminal environment. Struts immediately jumps to mind. Web 2.0 reminds me more of client / server applications although its not a perfect analogy.
It should not be surprising that architectures keep shifting back and forth over the years. Each is in some sense solving certain problems of the former. But it does lead to a certain amount of "rediscovering" something that used to be well understood. I suspect that many of the younger folks would be surprised to know that the virtualization driving the cloud dates back to 1972 and the IBM System/370 range of mainframes.