No, We Don't Need Walk-Ups (Or At Least Not Just Walk-Ups)

In reading arguments about Washington's height limits, one anti-height argument that I occasionally see is: "We don't need height for density-  we can just build 5-6 story buildings."  These kind of "walk-up" buildings typically can't afford elevators (except maybe at the high end of this range).  

Such walk-ups are perfectly fine for 30-year-old hipsters.  But in an aging society, walk-ups will become worthless for more and more people. Here's why: old people with brittle bones often have lots of trouble climbing stairs; in my experience this applies to people as young as 60.  So they simply cannot live in buildings where they have to climb a lot of stairs.   This means that multistory rowhouses are not a possibility; in fact, even single-story rowhouses (or the ground floors of multistory rowhouses) are often not usable by the elderly without significant retrofitting, since they often have stairs to create a sense of privacy and insulation from the street. 

So our constantly growing stock of seniors will either have to live in single-family-house sprawl, or they have to live with elevators.  And elevators require height.  That doesn't mean they have to live in 100-story skyscrapers- but it does mean that more of them will live in smaller mid- and high-rise buildings than some urbanists might like.