Sorry, dont buy it. Not that this will bother most people (and it may actually be easier for some) but there is no denying this is a major disadvantage.
For me, it means there will be no SlingBox, no logmein, no alternate calender like Pocket Informant, no TCMP. And when you clear your cache all your apps are gone...
Looks like I will have a slew of new articles to write now. I understand your perspective, but what you are describing is not what would happen with a well written web application.
I don't know a whole lot about this, but isn't one of the points about Ajax that you don't have to do that?
AJAX is a style of programming that leverages XHTML, CSS, JavaScript, usually some database integration, and server calls using the http-equiv command. It is the summation of all of these elements that makes what is referred to as AJAX.
To answer then Surur's post I quoted, a correctly written web app would be one part cookie and cache usage, and another part a web control (think like ActiveX) that a user has on their device. The user control tells the server that some snippet of the application has been installed - usually a runtime and server credentials. Depending then on the app, a person either has something that has to sit in an open browser window all the time, or a program that can go offline for some functionality and then make a call back to the server for updaing or new information.
In the case of the apps that were mentioned, LogMeIn would not need an app - it shouldn't anyways. TCMP/iTunes could run locally stored content, and then connect to a sever (something like MyStrands) for additoinal music or other content tie-ins.
If it was written right, Singbox could use FlashVideo to show the content and therefore only need a browser as well.
This is not to say that these apps would be as efficient as native apps, but that there is much that can be done if developers start to think about using a device, not just pushing out an app.
To go back to the Bible reading aanlogy, I had some conversations with the folks at eBible.com some time ago. I asked them if they would consider making their eBible website a hybrid appliciton. One where a person would be able to download and read the Bible normally (browser or native app), but then that connects to their other services and content as premium content. While they expressed interest, the effects of such an endavor means that a company has to give up some control of rudamentary content in order to make a compelling offering to keep people around. Web apps do that. There will be a ton of them at the iPhone launch and after, but only a few will show definitve benefit, and don't be surprised if MS Live is one of them.