Even if you never use them, you really do want them to be there. I'm often on a public stairway which combines heavy foot traffic and a fairly well hidden elevator. It really showcases what a nightmare it'd be if fat people everywhere suddenly decided that they were going to start using the stairs. Even with a large stairway it only takes one fat couple to block a huge crowd of people from going any faster than they are. And they are not going fast. Or even at the speeds one would expect from the elderly.