A summarizing post about web applications on mezzoblue says:
Of course, nobody seems to be talking about Macromedia's Flex and the continuing application development capabilities within Flash itself. Hindered by stigma that Flash is evil and purely about animation amongst developers that should be buying into Flex, it's hard to see this combination taking off; however, as a dark horse, it's a hard one to ignore on sheer numbers alone. Ninety-odd percent of web users have Flash installed, and Flash renders consistently cross-platform. Remember what Joel reminds us though: it's all about developers.Someone also brought Flash up in the comments of my last post.
There are some really cool Flash applications out there, and a lot of places where Flash is probably an excellent choice of platform. As long as you don't mind being a sharecropper. But it's more than that -- the licensing doesn't just affect developers.
Macromedia's model is one where they have to make developers happy, because developers are the ones who give them money. In their formative years the browsers didn't work to make developers happy, they competed for users, knowing that developers would follow users (this, in a time when users had some choice).
What makes developers happy? Or rather, the people who are always telling developers what to do? Control. "They" (the people who pay us developers) love to define what a user should and shouldn't be able to do. They have a general principle of denying everything that you don't explicitly allow. Who needs a back button? Who needs readable source? Why dissect the application into pieces (aka, pages)? An application might have structure in the IDE, but who cares about the deployed application. They wrote the application to render on one reader (Macromedia's) and they don't need nor care for any intermediate tools.
The result? Flash applications look nice, but they aren't that fun to use outside of small doses. Maybe it's because Flash is stretched when you implement an application using it -- maybe Flex will be better -- but that won't change the basic economics, and who Macromedia answers to. Open source, open standards, and non-commercial infrastructure isn't just good for developers, it's good for users.