This is how I see it:
I do understand the point this article is trying to put forward, but it very much depends on the problem that we are trying to solve with the software that is being built. In the end, we all design software to solve a certain problem that we have whether it be personal or at work.
I believe that the way in which we represent information is simply a design choice in the design phase and will depend on how “open” the software is and for what other purposes it will be used. The more closed source and “secret” the information needs to be the more complicated or obfuscated we will make it.
If we assume we are dealing with open source software, then I strongly support using formats which are simple to understand and reuse and follow some kind of standard where possible. It makes everyone’s live simpler.
One of the reasons for using a java applet may well be to try to hide the source as much as possible. I don’t think that a website which uses applets really intended other users to use that website as a source of weather data. In the end a well design peice of software will keep the GUI separate from data store/representation in which case it doesn’t matter that a java applet was used.
I agree with Tom: “Use the right tool for the job.”