The utility is the lower cognitive overhead of having all the UI that you don't need hidden, responsiveness, and having more lines of text visible on one screen. Similar reasons one might use WriteRoom.
I'm certain WriteRoom serves a niche. If it indeed was such a pain point in, WriteRoom should've achieved the scale of a .. Evrernote? Just saying that as developers, we tend to believe that our own little quirks is how everyone on the planet likes things to be.
