[diminish]

First, APIs are simply features exposed for developers' use. A map function not supported on a device, means the API isn't supported neither, and if your 3rd party development needs this API, it needs this function, namely access to this feature.

Second, you are confining yourself to fragmentation from a developer perspective, and fragmentation matters for other purposes too.

Third, your Android example is flawed; to just shuffler your argument; a function developed for Android 2.3 can run on 2.3 and later versions. And you only need ICS, in case you need a new "built-in feature" available in ICS. Alas, an ios6 app benefiting from new maps, won't work in a substantial proportion of ios devices.

Fourth, the other side of fragmentation is diversity; and you may write a corporate app, for a pen based samsung galaxy note, with a giant screen and give it to your sales users.