The web 2.0 applications are nice for the reasons you point (i.e., computer users don't also have to become system administrator), however, if you've ever tried to use gmail, for example, on an older or underpowered machine, you quickly discover that all those CPU cycles on your fast new machine are actually being quit well used by these "thin" AJAX applications. Seems pretty inefficient when you think about just how little whizzy UI there really is in gmail compared to, say, compiz. Not that I don't love gmail!