There's a third benefit. In most complex programs, the engine is 10-20% of the code and the UI is 80-90%. Contrast that to most web applications, where the ratio is flipped. Flipping this ratio has another huge benefit - the LOC drops dramatically and time-to-market is cut in half (or more).

By using the browser as a UI, all I (as the developer) have to do is generate well-formed DHTML. Since I'm targeting a platform (IE, NS, MZ, whatever), I can even tailor my code to that specific platform. If I want, I can play nice, but I don't have to. Since the code is installed on the user's machine, it's more acceptable for the code to be tailored to that specific setup.

Yes, the goal is to flip the standard paradigm of DHTML. *shrugs*