As a "web dinosaur", I've followed each and every technological evolution the web went through, and I could feel the direct impact they had on the way we used to do our web design.
The web design evolves in exactly the same pace as the web technologies, and I believe that the influence of the later over the former is the main factor that opens the paths we web designers take. Of course, I cannot say it is the only factor, but it is the predominant one.
Let's take the good old "web 2.0" (yeah! I hate this term either) style design as an example. I've read so many things about it, so many articles tried to define what the "web 2.0" look was! But none of them took into account the incredible burst of the web technology at the time.
They talked about the use of big, high quality images: of course, the data transfer was getting faster and faster, the ADSL connections were getting widely spread, and the pages, well, we were no longer creating our pages with thousands of table tags anymore. An HTML file that could easily make 20Kb was then weighting only 6Kb. Cool! We could finally let ourselves go a little and add smashing photos, no matter how big they were.
Well, that's surely not the only reason "web 2.0" sites were using big images. And there comes the second "web 2.0 look"" definition: simplicity and fewer columns (as it seemed). I must agree, those features have nothing to do with the web technology (or have they?), but they depend more of the type of sites that were spreading at that time. Lots of social web applications were appearing and their home pages were all about giving the user the desire to sign in. They had not much content in fact, hence less graphical artifacts, less columns, and big images.
And what about the new centered pages fever? This one is easy... Can this be something else then the growing popularity of wider screen resolutions then the old 800x600 pixels monitor? Think about it: an 800 pixels wide window is really very small. We had to take the entire place available if we wanted to balance our content without scrunching it too much. So, why bother centering it? Good guess!
Anyway, I don't think centered web pages appeared at the same time as "web 2.0" sites at all. It came earlier, but well, if some say that it is one of the web2.0 sites' design features, that's ok for me.
Web 2.0 or not, my data visualization aims only to put the web design evolution in the same context of web technologies and hardware evolution, trying to present a parallel between features, and in any way to justify our design choices.