I'm thinking of big halls, especially those that use chandeliers for light. The idea's simple: build a parabolic ceiling that uses mirrors, place the chandelier at the focus, and illuminate the entire hall with light. Since the light would be coming from the ceiling, it wouldn't be possible to "stand in someone's light" either, which would be great for e.g. exams. One would also be able to use just one light source for the entire hall. Why hasn't this been done?
I feel like I'm missing some obvious reason but I can't place it. One guess could be that big parabolic mirrors are expensive, but we have such mirrors elsewhere (e.g. for telescopes, science museums). It could be that such a hall would look really bright if one looks upwards (at the ceiling), but that could be mitigated by, e.g., placing a one-way mirror between the ceiling and ground level that allowed light down but not up. What am I missing?