That could be, although in the time I've been here I've seen people out on those balconies maybe twice, and one of those was when they were installing a microwave antenna. I get the impression they are there mostly as a place to shelter in an emergency.

Edit: Typically the stairs and elevators in buildings like that are pretty well locked down to prevent unauthorized access from inside. The elevator probably opens into a small lobby with heavy locked doors blocking access to the rest of the floor. The balcony doors may not have been so well secured.