I don't agree with you on that point. Android layouts are designed from the beginning to handle different screen sizes and proportions, pretty much like html. One of the iPhone's strong point has always been that you can design "pixel perfect" apps, so that your design is exactly what users see (as a contrast in Android you have to define "points of stretching" for your screens).

The point here is that you have to create a new layout for the iPhone 5 (if you don't want your app letterboxed) and this adds an extra layer of complexity to the development. Seeing that there are also rumors about a different form factor iPad you would then have to maintain 6 different layouts (standard/retina/16:9 for iPhone, standard/retina/new layout iPad). Well or 12 if you have specific landscape layouts.

Designing UI on Android apps can be a pain since you don't have the "pixel perfect" paradigm, which is a common criticism on Android from iPhone developers, but if you manage to get them right you can get away with a single xml layout (of course, you can able to make things more complicated).

It seems to me that Apple are getting themselves in a bit of a mess with this. The tradeoffs with the "pixel perfect" method haven't really materialized until now.

Maybe I'm just being over pessimistic with this and it will be a non-issue, I really can't tell at this point, but I see this as the greatest issue with the iPhone 5 (which in turn is probably the reason they didn't increase the screen size earlier).