Think about how we use a hotel. When we check in we have a reception counter that is typically taller than 4'-0" high.
Then once we are in our rooms, we have to hang things up in the closets, but the rods are typically higher than 54" high and it is difficult for "Little people" to use.
When designing in a Universal way, we need to keep in mind not only the mobility impaired, the visually and hearing impaired but the vertically challenged individuals who are extremely independent and would benefit from the sensitivity to give them a better quality of life. My friend Charles Stark sent me this article and I think it is worth reading to better understand this topic.