I have to put a very important note about the data: W3Schools data is not perfect because it is based on the data collected by people that visit their site, not necessarily the Internet as a whole. They even state this fact on the browser statistics page “W3Schools is a website for people with an interest for web technologies. These people are more interested in using alternative browsers than the average user” (they are referring to the fact that Firefox is usually reported higher on the w3schools.com than the Internet as a whole). We still can infer some trends with the data.
What is causing this?
There are several things that can be causing the trend:
Things to consider
Should we build our sites as Web 1.0 and then implement them as Web 2.0 on top of it? We had this discussion at Barcamp Madison in March. I think the consensus of the group was that if you wanted to broadest reach appeal in your application that it should work as both a classic web application and one that uses AJAX and DOM effects. There is always going to be a trade off on the reach of your application and the cost to get that reach.