Beginning with the origin of web applications at left hand side of the chart, we see that Ajax and HTML were designed to give application developers more power and capabilities when creating internet based applications.
It started off well enough, but Ajax never really took hold as well as initially expected. Ajax uses a combination of technologies that makes building the Client interface substantially more difficult than static web pages. It's performance is therefore relatively low when considering the effort that needs to be invested, since it's based on script that needs to be interpreted, rather than on compiled code.
The next step along the chart was the movement in the direction of plug-in's and Java. However, this also presented challenges, particularly with its compatibility with different browser types, with certain applets not being able to run properly.
The solution then, was for the industry to move to applications that run ‘outside the browser'. These apps run on the middleware stack but still use a runtime language such as Java or .NET.
This seems to be the most practical solution then, both in terms of cost and performance. Typical business application, we must remember, are characterized by complex and heavily loaded data. This data needs to be displayable and retrievable in an efficient manner.
The browser is simply not designed for that. To compound the problem, there are now so many different browser types out there (Internet Explorer, Firefox, Safari and now Google Chrome) that preparing the application to run on each is a coder's nightmare.
The solution then is obvious - scrap the browser altogether as a business application sandbox - and use a tool that has a dedicated business-optimized front-end layer.
You'll find it far more secure as well.