iOS7 has a swipe from the left gesture that will trigger the back event, for apps that support it. Long overdue imo and it helps some with what you're describing.
Back events as a whole are problematic. Android's OS back button behavior is application defined up until you're at the base "level" of the app, at which point the behavior is OS defined and it takes you to the home screen. That kind of state management isn't intuitive, and even though you should be able to just hit the app icon to go back(assuming a properly coded app), it's still an inconvenience if you fat finger the button one too many times. Discovery of what the button does for each app is also an annoying process as well.
The change to a swipe might reduce the accidental fat finger, but discovery is a nightmare for both the gesture itself and application specific behaviors for the back event.
I prefer an application button in both cases, especially because it makes it clear that this is something that will only effect the app, and will not have a weird OS interaction, taking me out of the app.
The issue with "swiping" gestures in general is that most users will never learn about them. Even if you introduce them visually in some kind of intro walkthough, they're too easy to forget.
The underlying problem that makes them a bad interaction paradigm, in my opinion, is that they have no affordances whatsoever. You just can't tell by looking at the UI that swiping left/right/up/down is going to have an effect.
For one thing, they're shown in Apple's promotional videos. How are users supposed to learn about any feature not represented by a button on screen? I'm thinking of the notification tray, control center, double-tap home button for multitasking, press home+power for screenshot, hold home button for Siri, and even older features like pinch to zoom and rotate.
Homebrewed swipe gestures, sure, but I don't think it's that big of a problem to introduce an app-wide swipe gesture. The problem with discoverability only shows up when it's in your own homebrewed component.
The affordances for swiping through Springboard seem to work pretty well. More important than the dots is the physicality of the animation. You can wiggle the current screen back and forth with a small motion and transition with a more dramatic one, but either way there's a clear directness to the interaction.
All swiping should work that way, and Apple is emphasizing the importance of "physical" dynamics in iOS 7.
That's a great point - I think it does make it a lot better when there's some kind of connection between a physical movement and the response from the app. The worst kind of swiping gestures are the ones where you have to get it just right, and then a menu "magically" appears out of nowhere.
I think another possible way of indicating the presence of a gesture might be through clever use of shading - for example, a subtle gradient on the edge of the screen where you can swipe, giving you the impression that there's something "just off the screen". I haven't actually seen this in an app yet - not sure why this isn't done more, especially for the Pull To Refresh trick.
