In any event one should be able to change the aspect ratio prior to taking the picture. It would be nice to take 16:9 or 16:10 photos and not have to crop afterwards.
The sensor is 4:3 so cropping just removes part of the image. Even if the iPhone had a setting to do wide screen, it would be still just cropping the 4:3 sensor. There are plenty of apps that you can crop as you wish.