This is just to use full power of creativity part during doing boring programmer work.
I’ve watched this course which revealed for me the power of Processing:
https://class.coursera.org/digitalmedia-001/class
The whole point is that you don’t need to make your program excellent from the first day of development. It simply possible that you will not have enough time and motivation to complete.
My idea is to use Processing for quick prototyping and then (only if the application is promising – you can check this with real users) – go ahead with more powerful solution.
Firstly – create a mockup which is just broken but have the ability to communicate an idea to the user. Only after that – fix and polish it.
That is why Processing was created for – to test, experiment and create quickly without much hassle and development tools.