This is my understanding of why this can't be done:
The art in the game is isometric so that what you see on the screen is basically a flat image. Because of this, the guys at Larian were able to save time by only drawing one side of most of the objects seen in-game (I'd imagine that all background objects are like this, since they won't be moved or rotated), so that a much larger game-world can be created in a shorter time.
The downside of this approach is that full camera rotation is impossible since the objects don't have full 3D models (I can't think of any isometric games that are exceptions to this) - small rotations can be simulated by stretching things, but a full rotation is impossible and implementing this would pretty much mean making all the art in the game world again several times over, not to mention the engine work required to implement the 3D nature of the world...
