How about this:

"What problem does a web application solve that a desktop GUI frontend to a network server does not?"

Browsers are huge beasts. If, looking at a single application, one could take away from the browser all the things that a particular application does not need, what would that application's size be? Given good UI libraries, perhaps a million times smaller?

Of course, it's the good old "Worse is better" again. I haven't lost hope, though. I'm sure we can come up with something better than the browser.

edit As an example of something vastly better that already exists in a stable form: http://www.rebol.com/docs/easy-vid.html

Seems like a pretty elegant language but it needs more parentheses.

accessibility as well.

I can access news.yc on my t-mobile dash, my mac, my desktop & my friend can access it on his iphone or ubuntu machine. Installed native apps can't do this, unless you install them, which requires download and os compatibility.

disabled people use accessibility differently. you might want to use ubiquity or platform-independence as alternative phrases.

But yes, i totally agree with you. multimodal data/application access is a beautiful thing.

You are right. But I have a question: what are network desktop applications like iTunes good for?

Nothing you can't get from Pandora (or Seeqpod).

I was going to add "unless you're not in a hotspot", but browsers are going to cache more and more, so that's not going to be as true.