Is Apple's way of releasing iOS showing its limits?

The way Apple update iOS is that it bundles everything, including the stock apps (I'll use Safari as an example). So to get the stock apps updated, you have to get the whole OS update. This started to show its ugly head, to me, back on the original iPad, where it didn't even get iOS6. I understand there are limitations on old hardware running new software that may have higher requirements in processing power, RAM, etc. However, there are also concerns about security updates. This was the negative of Android in the past. But now, I can be running Android 4.1 with pretty much all my Google apps updated to the latest version, including Chrome and the keyboard. Meanwhile, people on iOS 6 are stuck with older versions of all the stock apps if they don't/cannot upgrade to iOS 7.

The next ugly turn will be the iPhone 4. I bet iOS 7 will be the last update for it. Now you can argue that it's an old phone, but let's face it, a LOT of people have and still use it. I would think this is quite a concern from security perspective (assuming there are security issues with the older version of Safari, for example).

Thoughts? As more and more people using iDevices, I think Apple needs to rethink the way it pushes iOS updates. I thing at the very least they should make Safari standalone so it can be updated as needed, and give users with at least the previous version iOS access to an updated version.