iPhone devs who write native apps and then complain to Apple about the app store policies are stupid, because they are tilting at windmills when there is a much easier solution to the problem.
There's "good enough" and "excellent" - these are not the same thing. It seems like the webapp apologists are in the "good enough" camp, and they're certainly right: Apple's webapp facilities are good enough.
But they're not great, and great UI is the defining feature of the iPhone. If you lose it all you have is a piece of plastic that has fewer features than the competition. IMHO also, the constant settling for "good enough" UI is a hallmark of programmer-driven UI, which rarely results in usable apps by regular people.
Requiring iPod Touch owners to connect to wifi before they access your webapp just puts another hurdle between you and your users, one which they won't always be able to clear.
My main argument is, as a developer you KNOW what the App store approval process is like, it's been beaten to death all over the Internet. So either accept that you're going to have to play by Apple's rules or make a web app and save yourself the trouble. It's Apple's garden and we all just play in it.