[reubenswartz]

This may work in some situations, but unfortunately commercial building are typically very expensive to convert to residential. Think of an office tower with centralized plumbing and HVAC, with an open floor and no real interior walls. You've got to run plumbing and HVAC everywhere, add real(ish) walls, and depending on the size of the floor plate, there may not even be a good way to get light to the right places.