I never though about it before but that actually is a fascinating cultural shift.
White-collar workers today spend so much time sitting, and are so conscious of health and wanting to be active, that escalators aren't a luxury -- they're the antithesis of a healthy lifestyle.
If buildings necessarily express the values of the people in them, well values have changed. It's the age of Fitbit and walking around dense city centers and walking up stairs -- not being sedentary and driving and just standing on an escalator.
(While elevators are still mandated for disabilities, which escalators were never good for anyways.)