Millhouse, it shall improve: pedestrians don't walk on the top of streets, therefore you'll would be always underestimating the length in that way. Pedestrians cross using the well-named crosswalks, not road intersections. In many places (like here in my city, Curitiba, Brazil) isn't the same to walk in the left or right side of the street. If the current routing engines are flaky, they should adapt then, it shouldn't the other way around. Also it's officially deemed as a good practice that one shouldn't map for the renderer, nor for the router. 