A couple of days ago, my colleague here at ZDNet, Richard McManus wrote a post that talked about Zimbra and how their application doesn't perform well on IE. The exact title is "Zimbra performance issues highlight IE's inadequacies as web 2.0 platform". This is a perfect example of why these more advanced applications need to move beyond the browser. Until they do, they'll be plagued by performance issues and lose users despite having a good idea.
Ajax is a simple and elegant tool, which is why it's so powerful. There are a ton of good Ajax applications out there, and as a technology, it deserves all of the attention that it gets. However when developing any kind of application, you need to use the best tool for the job. In this case, Ajax falls far short of technologies like Flex, WPF, and OpenLaszlo. Now, I realize that only one of those products is out for commercial release, but companies looking to build rich, high-experience applications shouldn't be using Ajax, they should be looking at the next generation of RIAs.
The CEO of Zimbra, Satish Dharmaraj said that his application is "pushing the envelope of Ajax". But Ajax, just like everything, has limitations. As more applications with the richness of Zimbra come out, the developers using Ajax are going to run up against those limitations. This is eventually going to spur adoption of the RIA platforms. We'll probably have a year where very rich Ajax apps are going to be seen side by side with next generation RIA apps done in Flex or WPF. When that happens, allowing users and developers to see the technologies side by side, they're going to like what they see from the next generation. Ajax will continue to do what it does best, but where performance and interface matter, WPF, Flex or OpenLaszlo will be first choice.
There is also the question of whether or not Rich Internet Applications are really worth the overhead. One of Richard's posters quipped that Zimbra took 4 minutes to load while Gmail loads in less than 10 seconds - and he/she is absolutely right. Even if a great Flash application loads in 20 seconds, why not use Gmail, which loads in 10 seconds? Because richness is going to be a big value add, that's why. Applications that incorporate new levels of collaboration, multimedia and user experience are going to turn the web application world on its head. The line between the desktop and the web is going to blur, and the most important users, the ones at home, will be drawn to a richer experience. That in turn, is going to draw content providers and advertisers in a big way.
I like Ajax, but when you're trying to build applications for the cutting edge, look in a different direction. Ajax will only take you so far, and if you invest the time and energy in it, you'll find yourself on the outside looking in.