This is only a social problem if there is too much office space vacant at a given time. We would not want a city to have zero empty office space because that would show that there is an imbalance between supply and demand.
If there is a relatively small amount of vacant office space, it is a good thing. This keeps rents from getting to be excessively high. If rents get too high, businesses might be deterred from moving to the city and new businesses might be deterred from starting up because of the lack of affordable office space.
However, if there is too much vacant office space it can be a social problem. In this case, the lack of demand is probably an indication that the city’s economy is not doing well. The empty office space can also lead to other social problems if, for example, vagrants move in to space that is empty and unattended.