Rendering isn't the problem. Because of the original decision to use a fixed camera angle, the artists were able to take shortcuts designing the environment (ie simply leave out walls that you couldn't see from that angle). There is a colourful tree north of Cyseal that was clearly designed to look good from a specific angle, which looks a little flat with the camera at a different angle. To completely unlock the camera, someone would have to go through and fill in all the details that the artists were able to hide out of sight before.
