At the moment, some art assets are built around "the camera is fixed". Some are full 3D so it doesn't matter how you look at them or where the camera is, or where and how they are placed in the world, but when we said "the camera is fixed", the artists and level designers started working that way.
That means that if we would allow camera rotation, you'd see "ugly stuff" once in a while. Tricks you can pull with objects and level design (which makes the 3D objects lighter, which means we can put more objects in a larger world)... So we may not officially put it in, unless we change our minds and get design and art on our backs, or get people on forums go like "haha did you see that house, it has no left wall, stupid game, but with the game being moddable and all, I'm sure someone might mod it in.