^^ That's the northern face, and this is why... the proposal for Buckingham II.
The Auditorium Building is a landmark in world architecture, so it's pretty safe to assume that it will be there for the forseeable future. Roosevelt also owns the building, so the rules that limit windows along lot lines don't apply (since, for all intents and purposes, there is no lot line). You can put glass on that side and get great southern views. The north side, on the other hand, is a vacant lot with an active proposal for a building that will block any windows on that side. So you put service and circulation spaces along the northern side, and there's no need or reason for those spaces to have windows.