Like any simulator, RP1 lets developers test and refine the ideas more quickly than they could working with a real platform. RP1 also offers an important economy. A robot builder who develops a system using a simulator puts a lot of effort into getting his code to work. That effort should not be wasted when it's time to move on to the real thing. Rossum's Playhouse attempts to accomplish that end through the use of a client-server architecture.
Developers work on all sorts of systems, using all sorts of languages.
Some work on big Unix boxes, others on PicStics, or Lego systems. As I said above, I want them to be able to code for their target platform, in whatever language they need to use. My simulator happens to be written in Java. Now Java is my language of choice, but I don't expect everyone else to feel the same way. One solution is to go with a client-server architecture.