I remember when I first got into web development at the tender age of 12, when my class was tasked with making a website about the Rideau Canal in Ottawa, ON, Canada for a competition with other classes around the world (if I remember correctly we won nationally and finished second globally.) Back in those days, the good old web 1.o days, complexity was king. Your site could be about chameleons, but if it couldn't file your taxes and find you some extra deductions while playing music in the background and using seven different programming languages, it wasn't quite complex enough for the web. In other words, the more features you could pack in, the better. Bigger, bulkier sites were en vogue and they were knocking small sites out with their size and usefulness.
Then suddenly, cellphones, televisions, refrigerators, and, god-forbid, computers were connecting to the internet. Wireless was the new wave. All of a sudden these tiny cellphones couldn't handle big, bulky sites, therein lies the reason for the shift to Web 2.0. All of a sudden people realized that maybe a chameleon fansite might not need to be able to do your taxes to be useful, people realized that there was a new king, and it wasn't complexity. The usurper was design. Sites became leaner and meaner, and these tinier faster sites were destroying the gigantic remains of Web 1.o that failed to adapt. People realized that clutter on your site, like on your desktop is an eyesore. And this was a good thing.
Another side affect of this shift is that one school of design became dominant, tables, which typically deferred to the now obsolete and nearly extinct frames and iframes.
R.I.P. Frames and long live design."The only thing worse than democrats and republicans... Is when these pricks work together!" - Lewis Black