Sorry guys but I disagree..
If they are installed correctly, we can train staff to use them in the correct manner, they may need to use them when all else fails or are in a situation away from their regular place of work etc.
If we install them correctly in schools then the education at an early age can be achieved and developed.
A thought though, if in a fire situation with reduced or limited visibility you see an exit sign above a door, with direction arrow pointing down, head for it and using your training to the correct standard open the door and tentatively try to find the stair or ramp, you will slow down the evacuation. Surely the intention of these sign is as an aid to evacuation and not meant as a hinderance.
If on the other hand were someone to fall down a set of stairs when the sign didnt indicate the possibility of level change, would there be grounds for litigation??