Frivolously? Just because you don't know why they made a change doesn't make it frivolous. Other people have said it's because people tend to store their phones in their pocket upside-down (I know I do) and so it's nicer that way. This may be the reason, or they may have wanted to put other stuff at the top of the phone and the headphone jack was in the way. If it was just because of the phone being upside-down in your pocket, they've still put other stuff where the jack was (there's no empty space in the phone), and whatever they put there may or may not be able to be relocated (for example, it's possible that the extra space there is used for camera-related hardware).