Web Browser applications unquestionably off one significant advantage over Windows Desktop applications.
It is called zero deployment - they can be used anywhere, by anybody, at any time or many different devices – with zero application deployment requirements.
To execute Windows desktop application you need to deploy it to the user's desktop or to a server that the user has high speed access to. This process is expensive, complex, time consuming and error prone.
However, as a medium for deploying advanced desktop functionality, zero deployment is the Web browser application's only advantage. In all other respects, web browser applications are inferior to Windows desktop applications. For fundamental architectural, security and bandwidth reasons web browser applications will almost always produce relatively slower end-user responses with much poorer desktop integration capabilities.
At the core the attractiveness of using a web browser interface is (like almost everything) really about economics.Ultimately zero deployment is a very attractive economic proposition.
In other words, end-users tend to have web browser interfaces imposed on them by IT for significant and very real cost saving economic reasons rather than for productivity improvement reasons. Often they would much prefer to have the power, speed and flexibility of Windows desktop interfaces (e.g.: to the level of MS-Word and MS-Excel) but economics and the limits of technology means that they cannot.
You should never think that you are going to improve your end-users work life by giving them a browser interface in place of a well-designed Windows desktop one. You are giving them a browser interface to save money.
Getting the balance between the zero deployment economic reality and end-user expectations and requirements exactly right can be a complex equation. If you look on the Internet you can now find reports from various IT industry groups that describe situations where designers and developers have gotten this balance wrong. You may have experienced an imbalance in this area yourself.