I don't know how many times this whole "a camera - WHY, oh WHY, OMG, how stupid idea!" thing was already answered, but let me do this again: because there are SO MUCH MANY OTHER THINGS THAT YOU COULD DO WITH REAR-FACING CAMERA, other than "taking photos", for feck's sake!
Originally Posted by DJeremyC
Evernote, making quick "electronic" version of paper document to have it on a go, Augmented Reality. Sending email with a quick snap, on the go, or annotating it first, and then sending. Google googles, barcode readers, price comparison, product tags hot-linking.
Not to mention other tens if not hundred potential, creative usages - like that keyboard for Android, that shows you a picture on screen, what camera is looking at - so you can actually type and walk, without the risk of falling down an open manhole. Just an example.
...is it enough now, do you have your answer "WHY" now?