I dont think people buy a new phone for the battery.
But a lot of people buy new phones when their old phones suffer from sluggish performance - esp. around the time of a new version release.
(sluggish performance aka Apple's secret software gift).
People buy phones because
1. They want the latest and greatest
2. They upgrade every 2 or 3 years
3. A new feature that adds value to their use case
Now, anti Apple posters who cannot help themselves in this thread, well they wont be bothered by an Apple issue, they should be trolling elsewhere!