You're 100% right from a technical standpoint, but it's a bit hairier on the UI design side. A huge strength of iOS is that most iPhone apps look and behave li

You're 100% right from a technical standpoint, but it's a bit hairier on the UI design side. A huge strength of iOS is that most iPhone apps look and behave like most other iPhone apps, and that's because of the coherency provided by the UI framework and HIG. Asking developers to write their own CSS styling for widgets would result in a much more fragmented experience from app to app, which would detract from the platform as a whole (on top of a whole other slew of tiny UI touches added to UIKit, like the surprising complexity of the view-to-view transitions in CoreAnimation, that would be lost on 99% of app developers if asked to develop their own animations). One of the most interesting things Apple is working on that everybody seems to ignore is iAd Producer. They've basically created a full-fledged HTML5 app-building tool that recreates a large part of UIKit in JavaScript, but it's currently only good for iAd development. I'd love to see what would happen if they would let developers release apps built with the tool.