I feel rapid prototyping is only effective for smaller or static applications. When you are forced to start by coding the specifics (focusing on the UI) you lose touch with the generic, making it harder to change code. Management and customers like rapid prototyping because A. sense of progress is easier to gauge and B. lost time by failling to reuse code is not measurable.

But then some developers also over-engineer small applications, and rapid prototyping is a good model to fix this. In short, it all depends on the current culture of developers and management in a specific company IMO.

Tiago