I think it would be better if changing camera just changed the position that the camera is focused upon, so you could still move it around freely if you wanted. So basically changing the camera would just put it in a default position, and change the focus point, so you basically choose where you want to look at, and then you can change where you want to look from, if you want.

A lot of the fixed camera positions have big clipping issues as well, as they don't work well when finishing a scene. Nice idea as an addition, but not really properly implemented.