I run a company that develops a laboratory informatics platform for data intensive science applications that mix wet lab and analytics operations into single workflows, with gene sequencing as the motivating application - think LIMS with a pipeline and visualization engine, if you're familiar with the space. (Lab7 Systems, if you're curious - http://www.lab7.io/
When we started development a few years ago, we had to make the decision as to whether or not to build a desktop application or a browser-based application. At the time, this wasn't an easy decision. Some aspects of the UI are straightforward form-style interfaces, but others are graphics heavy visualizations of very large data sets (100+ GB in some cases). Scientific and information visualization have almost always benefitted from local graphics contexts and native rendering engines. In addition, the data decomposition tasks often require efficient implementations in compiled languages. Our platform also controls analysis processes on large clusters, another task not well suited for the browser.
We gambled a bit and decided that the browser would be our primary user interface. Two trends at the time helped us make the decision (and luckily they both held steady):
As few other considerations helped us make the call:
(1) Our platform is a multi-user system. A desktop client would add to the support burden for our customers.
(2) Our backend needs to integrate with compute clusters, scientific instruments, and large, high-performance file systems. It is server-based, regardless of the client.
(3) The data scales we were dealing with also required "out-of-core" (to use an older term) algorithms for redenering, so the client would never get entire data sets at once.
(4) REST/json... XML, XMLRPC, SOAP, and all the others are a pain to develop for (I speak from experience), REST/json significantly reduced the amount of code we needed to maintain state between the client and server.
Personally, I can't imagine ever writing a desktop application again. The browser is just too convenient and, in the last few years, finally powerful enough for most tasks.