from what you are saying it seems android is more lenient about allowing you to target old devices.
They are, which is why software quality on Android lags iOS.
Apple at the moment does not let you submit to the app store anything targeting anything under iOS5 (a somewhat recent change after 6.0 had been out for a while).
This may mean some older devices drop out - but at this point the only devices out are some 1st gen iPod touches and the very first iPhone (not even the iPhone 3G which can run iOS5). That is not unreasonable and means that applications generally make use of new and advanced system features sooner rather than never.
In a world where Android developers pretty much have to target 2.0 devices as a base, you lose some ability to use advanced features to make a better app. That is dragging down quality all over and is only going to become more of an issue as iOS framework features advance...