I would have to respectfully disagree. There are many departments in the North east that still have spiral stairscases and fire poles. The fire poles are the fastest and safest way to get down.
If trained properly in their use and the holes are protected with a device, the fire pole is actually safer than stairs. Injuries may be slightly higher but less severe than a fall down the steps.
"Injuries may be slightly higher but less severe than a fall down the steps."
There's the problem right there. There is a higher instance of injuries while using a fire pole than with using the stairs. By your own statement, you're less apt to be injured while using the stairs.