In the building where I work, the stairwell doors are also locked from the stairwell side to keep people off floors that they can't access by the elevator. However, in a fire situation, they actually unlock to allow people to cross over to the other stairwell if one is compromised by smoke or heat.

The doors to our suite open on power failure. We also have emergency release pulls to open the doors in case the usual sensors don't unlock them when someone approaches from the inside; just in case we need to leave in a hurry.