I was in the Seattle/Tacoma airport today, and I noticed quite a few people taking the stairs even though they're flanked by escalators. It's been my impression lately that more people are using stairs than even five years ago. I used to be the only weirdo on the stairs, but today I shared them with about ten other people. I know Seattle isn't necessarily representative of the nation as a whole, but I (optimistically) think of it as the vanguard in this respect.
One of the healthiest things a person can do is build exercise into daily life. You don't have to be Usain Bolt or Lance Armstrong to reap the benefits of exercise. In fact, evidence is accumulating that moderate exercise is healthier than extreme exercise. Taking the stairs instead of the elevator/escalator, walking or jogging even a modest amount, or standing for part of the day, can have an immediate, measurable impact on metabolic health (1).
Maybe it's macho, but I'll feel defeated the day I need a giant energy-guzzling machine to take me up a 15 foot incline. I have legs, and I intend to use them. Escalators are good for people who are disabled or have very heavy bags, but the rest of us have an opportunity to use our bodies in a natural and healthy way. Part of the problem is how buildings are designed. Humans tend to take the path of least resistance, and if the first thing we come across is an elevator, and the stairs are grimy and tucked away down some side hallway, we'll tend to take the elevator. Architects in some places are building in more prominent stairways to encourage gentle exercise throughout the day.