Inputting text on the iPhone can be a tedious task. It's not so much the typing. But due to limited display space, editing can be irksome. It seems like doing things such as copying or deleting text are more complicated than they need to be.
Case in point, try typing a lengthy message in your Messages app. Now delete the whole thing. As it stands, the fastest way to do this is to tap on your text, 'Select All' and then delete it. But as with most things in iOS, it could always be faster....