Eh -- most home offices tend to end up in bedrooms, which in the US are obligated to have a window that a person could fit through (or to have some other secondary exit aside from a door).
One problem is where the window faces. A north-facing window, or a window facing into a hillside or into a courtyard, does not allow sufficient sunlight. In London, my flat is in a Victorian terraced house, and the bedroom I'd use as a home office has a window which only has views of the house next door, and very little natural light. (That said, probably still more natural light than I got in my office, where I'm essentially in a corridor.)