I agree completely. My hope is that AppStore will become optional, rather than the exclusive way to get apps on the iPhone.
But I do think it was a wise decision to start out with the AppStore as the one exclusive way to get on it, and judging from their phenomenal success in both sales and attracting developers, it was probably a smart choice.
Lest not forget, the AppStore makes it extraordinarily easy to buy and download apps. Only by making it the exclusive way to get apps on the iPhone were they able to make sure that users found the experience of buying and downloading apps so effortless that it makes impulse purchases super simple. And, safe! iPhone users do not worry about anything on the AppStore containing viruses or malware.
Now, as what they refer to as a "power user", I'd like to be able to just download any app from anywhere and take my chances. But I understand that Apple has to take more than just my preferences into consideration. I believe it is actually not in their best interest to do that — even though it would suit me better. If I were Apple, I'd keep the AppStore the exclusive way to get apps on the AppStore. I'd work on continuously improving the experience and interaction with developers, of course, but I'd keep it a walled garden, approval process and all.
Pleasing power users such as you and me simply doesn't make sense in the big picture, because it would fracture the developer community. Some apps would be on the app store, some on the web. Users would feel safer getting apps from the AppStore, but as recommendations come from friends using apps from the web, soon enough you'd have regular users downloading apps from the web too. And following that you'd have viruses and malware. While users could still just stick to downloading from the AppStore if they wanted to be safe, Apple would still have to deal with malicious apps, problems and trust issues. This, they just don't need, and pleasing the relatively few power users just doesn't make any sense, considering the sacrifice.
Though I'd be just fine with it, I understand very well why Apple does not prioritize my needs in this.