For nothing? You clearly have never designed an app before. Positioning and sizing content to fit within the current resolution of the iPhone can be a challenge, especially if there is a lot of content. Scaling up for this reason alone would be an enormous relief for app designers / developers and greatly improve the user-experience for customers.
I started in web design and development a long time ago (before everyone and their grandma entered) and remember the standard screen resolution was something ridiculous like 800x600. It limited the creative possibilities. As the resolution went up, the quality of websites improved with it. We'll see the same thing happen (to an extent) with phones.
More space = more creative possibilities.
Well I guess they're doing it for something then, aren't they?