Who told you its unsupported feature? The only thing that isn't supported is the rotating mechanism. How would rotate every single element in GUI to fit the rotated mode while keeping everything visible and use-able.
There is already an active thread talking about this and he decided to start a new one?! (He is even in that thread!)
I didn't post here to discourage anyone ,but to give more reason why its currently isn't possible (Which by harmattan is more likely to happen then now) and no need to say that I am not against this idea (as actually people normally handling the phone with one hand)
By the way if you need to see problem from a graphical way, I wont mind making some picture to show what I am talking about in a better way.