Which is why my idea is very practical.
No parachutes, no cable cars going to the ground or other buildings, just an inexpensive and simple solution. If you have to leave the building, but your route to the stairs is blocked by fire or debris, simply slide down a pole to the next floor and take the stairs from there. The simple, redundant safety of this idea would be well worth the modest cost of retrofitting existing buildings.
Lee, (Holy Bin Laden Batman! an emergency....to the bat poles!)