It's not a make or break kind of thing, but it's something I would use pretty often and always wondered why it wasn't there. Awkward selecting apps when they are rotated 90 degrees. A lot of people use their iPhones in landscape a good percentage of the time. I find it good for many games, Netflix or Amazon video, etc. Hopefully this is coming to iPad as well, where landscape is probably the dominant orientation.
Not sure why this couldn't be implemented on the 6 though as well.