The news broke today that Joost, the company which in a lot of ways was on the forefront of rich media, is canning its signature desktop client in favor of a purely web based portal. As a big proponent of desktop applications in general, and especially these hybrid applications which provide desktop functionality, I'm disappointed. And I've got a few thoughts on why so that others in the space don't make the same mistake.
Content - Aside from a couple of niche shows, Joost just didn't have the content draw that a site like Hulu has. Content is king and new content seems to be in demand. Joost couldn't keep up.
Use of the Desktop - I'm not really sure why Joost used the desktop. It didn't provide any desktop-like features. You couldn't save things to your hard drive to watch them offline. Essentially Joost was just a desktop application that let you go full screen. When Joost was released, the web didn't have that, but Silverlight and Flash Player advanced enough where it became trivial to do in the browser.
Lack of Link to the Web - Joost had a "Share" button, but it only used IM and Email. People want to share and embed things on their MySpace/Facebook pages. This is something I think a lot of rich media desktop apps (including Adobe Media Player) don't get. If you want to do a desktop client you have to provide the benefits of the desktop in the context of the web. Let people take content from the desktop player and embed/share it. Ideally, even provide a way to access a bulk of the content from a web portal.
In the end I think a hybrid approach is the way of the world going forward. Despite the buzz from Chrome, the desktop still has a lot of benefits as an application platform. But the web browser has to be central to every strategy. The companies that can easily blend those to worlds - and then incorporate the mobile world as well - will have a leg up on everyone else.