How about some business reasons?
- Don't have to test on multiple browsers. - Can upgrade the browser engine automatically with application updates and tie new features to iTunes version - Less risk of HTML hacking (source is much harder to get to), increases entrance barrier - Long term goal of familiarizing Windows users with a mac style interface.
Obviously Apple is doing fine without me as a customer, so what can I say...
however, unless you mean explicitly browsing, in which case i might be inclined to agree because of the iTunes store links that only work in iTunes...that are useless if you don't have iTunes installed.
I am surprised that it is still possible to buy applications for OS X anywhere. Why don't they tie OS X to the iTunes store as well?
In fact, why doesn't Apple just create it's own internet, completely isolated from the real internet?
Edit: one reason I can accept (just barely): pushing apps directly onto the phone if bought in the shop. I still think there should be a way to view the apps available in a browser.