iOS eschews the concept of a user-accessible file system, and that may well never change. But perhaps Apple could at least take a single step in that direction, by offering Dropbox-like file access to documents you store in iCloud. That one step, with a simple API for developers to offer access to said files as appropriate, would mean that any compatible app could, say, open your iCloud-stored text and Word documents, images, and so on.
Multitasking, multitasking, multitasking
Double-tapping the Home button to navigate between apps is a convenient feature. The fact that apps can freeze their state and resume it nearly instantly is also good. Background audio, VoIP, GPS functionality--these are all good, as well. But iOS could do more to support active multitaskers.
For example, while that multitasking bar you get when you double-tap the Home button is good, it's far from great. A Mission-Control-inspired interface, showing screens from your recently opened apps, might offer far more utility.
I'd also (still) love the ability to selectively grant some apps the ability to fetch data even when they're in the background. If my social networking, newsreading, and ebook apps could--even only once a day--poll for new content without my needing to launch them, I'd never run the risk of getting on the bus to Manhattan with my Wi-Fi only iPad mini, just to discover that all those apps were empty or full of stale content.
Apple, as always, will do what it wants. iOS 7 will likely come out in 2013, replete with new features we love and likely a few that confound us. We'll all rush to download it, presuming our iOS devices support it.
But as you continue to encounter competitors' operating systems in the wild--with their occasionally superior features--don't be surprised if you find your eye starting to wander in their direction.