First off, let's get one thing straight: WrongRoom is not WriteRoom, nor is it made by the same folks. WriteRoom is made by Hog Bay Software, a completely unaffiliated entity. Let there be no ambiguity please.
Next, please understand that I would actually recommend that you buy WriteRoom if you are serious about writing in a distraction free setting. WriteRoom has a variety of options and features that WrongRoom just doesn't have, so please, get WriteRoom if you need what it has to offer.
So, why did I write it? Well, partly for fun (as my first OSX app), and partly because I just can't stand timed-trials. I wanted there to be a freeware alternative out there for OSX. Voila.