"tell me I'm wrong when I say the guy hit the nail on the head"

You're wrong *grin*. (Well, you did ask.)

I absolutely agree with Tim's analysis as a warning of potential dangers of prototyping, but I absolutely disagree with his argument that these are universal laws. My own experience of prototyping has been entirely favourable -- indeed contrary to Tim's analysis we have found prototypes invaluable for getting the inevitable mistakes out of the way quickly and without commitment.

As I said on my weblog, I don't know whether Tim's been unlucky or I've been lucky. If you've seen the same problems as Tim has, well, sorry. But that's bad prototyping, not a "universal law."

I'd venture that you've been lucky. I can't count the times where I've thrown together a quick "mockup" or "proof of concept" that gets slightly adjusted (maybe some error handling added) and suddenly becomes the production app.

I agree that prototyping can help you learn about some of the pitfalls of the task at hand, and for that, it's valuable. I find, though, that management (in that nebulous, men-in-black sense) sees the prototype and then says, "Why invest time in rewriting? It's already done! Just clean up any messy parts and call it good. On to the next project!" They fail to realize that, due to time constraints and the fact it's "just a prototype," the WHOLE THING is the "messy part."

I'm hoping to break that cycle with the next project I'm on - we have a prototype now, and my next project is to work with a team and make a production app out of it. We shall see.

And, hey, if I can somehow escape the universal laws, maybe I'll concede the idea that they aren't universal. :)