Well, a camera that can't take the picture you want is as useless as the one sitting at home. And iPhone may be, in some cases, a camera that simply can't do what you want. It's a cellphone. Of course, you won't carry a DSLR camera with you all the time, and even that isn't enough, think about lenses, flash, tripod… but iPhone won't magically replace all that, when you actually need it.