Not sure if it counts as a design element, but pick up truck bed heights. The bed height of full size 2WD pickup trucks seems to be growing in height at about the same rate as an elementary school kid. This is based off 3 comparison trucks. My dad has a 2000 Dodge Ram 2WD work truck, my 2011 Silverado WT 2WD is a good 4" taller, got a loaner 2017 Silverado WT 2WD a few weeks ago, it was 4" taller than my 2011! At this rate, by 2040 anyone less than 8 feet tall is going to require a step ladder to reach the bed of a truck.